8 (eight) is the

_{21} polytopes 2_{21}, 3_{21}, and 4_{21} are the only semiregular ( Gosset) polytopes. Collectively, the k_{21} family of polytopes contains eight figures that are rooted in the _{21} honeycomb that represents the arrangement of vertices of the eight-dimensional $\backslash mathrm\; E\_$ lattice, and made of 4_{21} _{21} honeycomb, which is the only affine semiregular _{21} family. There are no other finite semiregular polytopes or honeycombs in dimensions ''n'' > 8.

^{8} is yotta (Y), and for its reciprocal, yocto (y).
* In liquid measurement (

"''Maha-lakshmi, Dhana-lakshmi, Dhanya-lakshmi, Gaja-lakshmi,

Santana-lakshmi, Veera-lakshmi, Vijaya-lakshmi and Vidhya-lakshmi''" *There are eight ''nidhi'', or seats of wealth, according to

—ramifies as the Noble Eightfold Path">—ramifies as the Noble Eightfold Path and the Buddha emphasizes the importance of the eight attainments or jhanas.
* In Mahayana Buddhism, the branches of the Eightfold Path are embodied by the Eight Great Bodhisattvas: (Manjusri, Vajrapani, Avalokiteśvara, Maitreya, Ksitigarbha, Nivaranavishkambhi, Akasagarbha, and Samantabhadra (Bodhisattva), Samantabhadra). These are later (controversially) associated with the Eight Consciousnesses according to the natural number
In mathematics, the natural numbers are those numbers used for counting (as in "there are ''six'' coins on the table") and ordering (as in "this is the ''third'' largest city in the country").
Numbers used for counting are called ''Cardinal n ...

following 7 and preceding 9.
In mathematics

8 is: * acomposite number
A composite number is a positive integer that can be formed by multiplying two smaller positive integers. Equivalently, it is a positive integer that has at least one divisor other than 1 and itself. Every positive integer is composite, prime, ...

, its proper divisor
In mathematics, a divisor of an integer n, also called a factor of n, is an integer m that may be multiplied by some integer to produce n. In this case, one also says that n is a multiple of m. An integer n is divisible or evenly divisible by ...

s being , , and . It is twice 4 or four times 2.
* a power of two
A power of two is a number of the form where is an integer, that is, the result of exponentiation with number two as the base and integer as the exponent.
In a context where only integers are considered, is restricted to non-negative ...

, being 2 (two cubed), and is the first number of the form , being an integer greater than 1.
* the first number which is neither prime
A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only ways ...

nor semiprime
In mathematics, a semiprime is a natural number that is the product of exactly two prime numbers. The two primes in the product may equal each other, so the semiprimes include the squares of prime numbers.
Because there are infinitely many prime nu ...

.
* the base of the octal
The octal numeral system, or oct for short, is the radix, base-8 number system, and uses the Numerical digit, digits 0 to 7. This is to say that 10octal represents eight and 100octal represents sixty-four. However, English, like most languages, ...

number system, which is mostly used with computer
A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...

s. In octal, one digit represents three bit
The bit is the most basic unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represente ...

s. In modern computers, a byte
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit ...

is a grouping of eight bits, also called an octet
Octet may refer to:
Music
* Octet (music), ensemble consisting of eight instruments or voices, or composition written for such an ensemble
** String octet, a piece of music written for eight string instruments
*** Octet (Mendelssohn), 1825 compos ...

.
* a Fibonacci number
In mathematics, the Fibonacci numbers, commonly denoted , form a sequence, the Fibonacci sequence, in which each number is the sum of the two preceding ones. The sequence commonly starts from 0 and 1, although some authors start the sequence from ...

, being plus . The next Fibonacci number is . 8 is the only positive Fibonacci number, aside from 1, that is a perfect cube.
* the only nonzero perfect power
In mathematics, a perfect power is a natural number that is a product of equal natural factors, or, in other words, an integer that can be expressed as a square or a higher integer power of another integer greater than one. More formally, ''n'' ...

that is one less than another perfect power, by Mihăilescu's Theorem
Catalan's conjecture (or Mihăilescu's theorem) is a theorem in number theory that was conjectured by the mathematician Eugène Charles Catalan in 1844 and proven in 2002 by Preda Mihăilescu at Paderborn University. The integers 23 and 32 are ...

.
* the order of the smallest non-abelian group all of whose subgroups are normal.
* the dimension of the octonion
In mathematics, the octonions are a normed division algebra over the real numbers, a kind of hypercomplex number system. The octonions are usually represented by the capital letter O, using boldface or blackboard bold \mathbb O. Octonions have e ...

s and is the highest possible dimension of a normed division algebra
In mathematics, Hurwitz's theorem is a theorem of Adolf Hurwitz (1859–1919), published posthumously in 1923, solving the Hurwitz problem for finite-dimensional unital real non-associative algebras endowed with a positive-definite quadratic form. ...

.
* the first number to be the aliquot sum of two numbers other than itself; the discrete biprime , and the square number .
A number is divisible by 8 if its last three digits, when written in decimal
The decimal numeral system (also called the base-ten positional numeral system and denary or decanary) is the standard system for denoting integer and non-integer numbers. It is the extension to non-integer numbers of the Hindu–Arabic numeral ...

, are also divisible by 8, or its last three digits are 0 when written in binary
Binary may refer to:
Science and technology Mathematics
* Binary number, a representation of numbers using only two digits (0 and 1)
* Binary function, a function that takes two arguments
* Binary operation, a mathematical operation that t ...

.
A polygon
In geometry, a polygon () is a plane figure that is described by a finite number of straight line segments connected to form a closed ''polygonal chain'' (or ''polygonal circuit''). The bounded plane region, the bounding circuit, or the two toge ...

with eight sides is an octagon
In geometry, an octagon (from the Greek ὀκτάγωνον ''oktágōnon'', "eight angles") is an eight-sided polygon or 8-gon.
A '' regular octagon'' has Schläfli symbol and can also be constructed as a quasiregular truncated square, t, whi ...

. The sides and span
Span may refer to:
Science, technology and engineering
* Span (unit), the width of a human hand
* Span (engineering), a section between two intermediate supports
* Wingspan, the distance between the wingtips of a bird or aircraft
* Sorbitan ester ...

of a regular octagon
In geometry, an octagon (from the Greek ὀκτάγωνον ''oktágōnon'', "eight angles") is an eight-sided polygon or 8-gon.
A '' regular octagon'' has Schläfli symbol and can also be constructed as a quasiregular truncated square, t, whi ...

, or truncated square
In Euclidean geometry, a square is a regular quadrilateral, which means that it has four equal sides and four equal angles (90-degree angles, π/2 radian angles, or right angles). It can also be defined as a rectangle with two equal-length adj ...

, are in silver ratio
In mathematics, two quantities are in the silver ratio (or silver mean) if the ratio of the smaller of those two quantities to the larger quantity is the same as the ratio of the larger quantity to the sum of the smaller quantity and twice t ...

, and its circumscribing square
In Euclidean geometry, a square is a regular quadrilateral, which means that it has four equal sides and four equal angles (90-degree angles, π/2 radian angles, or right angles). It can also be defined as a rectangle with two equal-length adj ...

has a side and diagonal length ratio of ; with both the silver ratio and the square root of two
The square root of 2 (approximately 1.4142) is a positive real number that, when multiplied by itself, equals the number 2. It may be written in mathematics as \sqrt or 2^, and is an algebraic number. Technically, it should be called the princip ...

intimately interconnected through Pell number
In mathematics, the Pell numbers are an infinite sequence of integers, known since ancient times, that comprise the denominators of the closest rational approximations to the square root of 2. This sequence of approximations begins , , , , an ...

s, where in particular the quotient of successive Pell numbers generates rational approximations for coordinates of a regular octagon
In geometry, an octagon (from the Greek ὀκτάγωνον ''oktágōnon'', "eight angles") is an eight-sided polygon or 8-gon.
A '' regular octagon'' has Schläfli symbol and can also be constructed as a quasiregular truncated square, t, whi ...

. With a central angle
A central angle is an angle whose apex (vertex) is the center O of a circle and whose legs (sides) are radii intersecting the circle in two distinct points A and B. Central angles are subtended by an arc between those two points, and the arc le ...

of 45 degrees and an internal angle
In geometry, an angle of a polygon is formed by two sides of the polygon that share an endpoint. For a simple (non-self-intersecting) polygon, regardless of whether it is convex or non-convex, this angle is called an interior angle (or ) if ...

of 135 degrees, regular octagons are able to tessellate
A tessellation or tiling is the covering of a surface, often a plane, using one or more geometric shapes, called ''tiles'', with no overlaps and no gaps. In mathematics, tessellation can be generalized to higher dimensions and a variety of ...

two-dimensional space alongside squares in the truncated square tiling
In geometry, the truncated square tiling is a semiregular tiling, semiregular tiling by regular polygons of the Euclidean plane with one square (geometry), square and two octagons on each vertex (geometry), vertex. This is the only edge-to-edge ti ...

, as well as fill a plane-vertex with a regular triangle
A triangle is a polygon with three Edge (geometry), edges and three Vertex (geometry), vertices. It is one of the basic shapes in geometry. A triangle with vertices ''A'', ''B'', and ''C'' is denoted \triangle ABC.
In Euclidean geometry, an ...

and a regular icositetragon
In geometry, an icositetragon (or icosikaitetragon) or 24-gon is a twenty-four-sided polygon. The sum of any icositetragon's interior angles is 3960 degrees.
Regular icositetragon
The '' regular icositetragon'' is represented by Schläfli symbol ...

. The Ammann–Beenker tiling
In geometry, an Ammann–Beenker tiling is a nonperiodic tiling which can be generated either by an aperiodic set of prototiles as done by Robert Ammann in the 1970s, or by the cut-and-project method as done independently by F. P. M. Beenker.
Th ...

is a nonperiodic tesselation of prototile
In the mathematical theory of tessellations, a prototile is one of the shapes of a tile in a tessellation.
Definition
A tessellation of the plane or of any other space is a cover of the space by closed shapes, called tiles, that have disjoint in ...

s that feature prominent octagonal ''silver'' eightfold symmetry, and is the two-dimensional orthogonal projection
In linear algebra and functional analysis, a projection is a linear transformation P from a vector space to itself (an endomorphism) such that P\circ P=P. That is, whenever P is applied twice to any vector, it gives the same result as if it wer ...

of the 8-8 duoprism. In number theory, figurate number
The term figurate number is used by different writers for members of different sets of numbers, generalizing from triangular numbers to different shapes (polygonal numbers) and different dimensions (polyhedral numbers). The term can mean
* polygon ...

s representing octagons are called octagonal number
An octagonal number is a figurate number that represents an octagon. The octagonal number for ''n'' is given by the formula 3''n''2 - 2''n'', with ''n'' > 0. The first few octagonal numbers are
: 1, 8, 21, 40, 65, 96, 133, 176, 225, 280, 34 ...

s.
A cube
In geometry, a cube is a three-dimensional solid object bounded by six square faces, facets or sides, with three meeting at each vertex. Viewed from a corner it is a hexagon and its net is usually depicted as a cross.
The cube is the only r ...

is a regular polyhedron
A regular polyhedron is a polyhedron whose symmetry group acts transitively on its flags. A regular polyhedron is highly symmetrical, being all of edge-transitive, vertex-transitive and face-transitive. In classical contexts, many different equival ...

with eight vertices that also forms the cubic honeycomb
The cubic honeycomb or cubic cellulation is the only proper regular space-filling tessellation (or honeycomb) in Euclidean 3-space made up of cubic cells. It has 4 cubes around every edge, and 8 cubes around each vertex. Its vertex figure is a re ...

, the only regular honeycomb in three-dimensional space. Through various truncation operations, the cubic honeycomb
The cubic honeycomb or cubic cellulation is the only proper regular space-filling tessellation (or honeycomb) in Euclidean 3-space made up of cubic cells. It has 4 cubes around every edge, and 8 cubes around each vertex. Its vertex figure is a re ...

generates eight other convex uniform honeycombs under the group $\_3$. The octahedron
In geometry, an octahedron (plural: octahedra, octahedrons) is a polyhedron with eight faces. The term is most commonly used to refer to the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet at ea ...

, with eight equilateral triangle
In geometry, an equilateral triangle is a triangle in which all three sides have the same length. In the familiar Euclidean geometry, an equilateral triangle is also equiangular; that is, all three internal angles are also congruent to each othe ...

s as faces
The face is the front of an animal's head that features the eyes, nose and mouth, and through which animals express many of their emotions. The face is crucial for human identity, and damage such as scarring or developmental deformities may affe ...

, is the dual polyhedron
In geometry, every polyhedron is associated with a second dual structure, where the vertices of one correspond to the faces of the other, and the edges between pairs of vertices of one correspond to the edges between pairs of faces of the other. ...

to the cube and one of eight convex deltahedra. The stella octangula
The stellated octahedron is the only stellation of the octahedron. It is also called the stella octangula (Latin for "eight-pointed star"), a name given to it by Johannes Kepler in 1609, though it was known to earlier geometers. It was depict ...

, or ''eight-pointed star'', is the only stellation
In geometry, stellation is the process of extending a polygon in two dimensions, polyhedron in three dimensions, or, in general, a polytope in ''n'' dimensions to form a new figure. Starting with an original figure, the process extends specific el ...

with octahedral symmetry
A regular octahedron has 24 rotational (or orientation-preserving) symmetries, and 48 symmetries altogether. These include transformations that combine a reflection and a rotation. A cube has the same set of symmetries, since it is the polyhedr ...

. It has eight triangular faces alongside eight vertices that form a cubic faceting
Stella octangula as a faceting of the cube
In geometry, faceting (also spelled facetting) is the process of removing parts of a polygon, polyhedron or polytope, without creating any new Vertex (geometry), vertices.
New edges of a faceted pol ...

, composed of two self-dual tetrahedra
In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. The tetrahedron is the simplest of all the o ...

that makes it the simplest of five regular compound polyhedra. The cuboctahedron
A cuboctahedron is a polyhedron with 8 triangular faces and 6 square faces. A cuboctahedron has 12 identical vertices, with 2 triangles and 2 squares meeting at each, and 24 identical edges, each separating a triangle from a square. As such, it ...

, on the other hand, is a rectified cube or rectified octahedron, and one of only two convex quasiregular polyhedra. It contains eight equilateral triangular faces alongside six squares, whose first stellation
In geometry, stellation is the process of extending a polygon in two dimensions, polyhedron in three dimensions, or, in general, a polytope in ''n'' dimensions to form a new figure. Starting with an original figure, the process extends specific el ...

is the cube-octahedron compound. The hexagonal prism
In geometry, the hexagonal prism is a prism with hexagonal base. Prisms are polyhedrons; this polyhedron has 8 faces, 18 edges, and 12 vertices..
Since it has 8 faces, it is an octahedron. However, the term ''octahedron'' is primarily used to ...

, which classifies as an irregular octahedron that is a parallelohedron
In geometry, a parallelohedron is a polyhedron that can be translated without rotations in 3-dimensional Euclidean space to fill space with a honeycomb in which all copies of the polyhedron meet face-to-face. There are five types of parallelohedr ...

, like the cube, is able to tessellate
A tessellation or tiling is the covering of a surface, often a plane, using one or more geometric shapes, called ''tiles'', with no overlaps and no gaps. In mathematics, tessellation can be generalized to higher dimensions and a variety of ...

space as a three-dimensional analogue of the hexagon
In geometry, a hexagon (from Ancient Greek, Greek , , meaning "six", and , , meaning "corner, angle") is a six-sided polygon. The total of the internal angles of any simple polygon, simple (non-self-intersecting) hexagon is 720°.
Regular hexa ...

. The gyrobifastigium
In geometry, the gyrobifastigium is the 26th Johnson solid (). It can be constructed by joining two face-regular triangular prisms along corresponding square faces, giving a quarter-turn to one prism. It is the only Johnson solid that can tile ...

, with four square faces and four triangular faces, is the only Johnson solid
In geometry, a Johnson solid is a strictly convex polyhedron each face of which is a regular polygon. There is no requirement that isohedral, each face must be the same polygon, or that the same polygons join around each Vertex (geometry), ver ...

that is able to tessellate space, while the truncated octahedron
In geometry, the truncated octahedron is the Archimedean solid that arises from a regular octahedron by removing six pyramids, one at each of the octahedron's vertices. The truncated octahedron has 14 faces (8 regular hexagon, hexagons and 6 Squa ...

, also a parallelohedron, is the permutohedron
In mathematics, the permutohedron of order ''n'' is an (''n'' − 1)-dimensional polytope embedded in an ''n''-dimensional space. Its vertex coordinates (labels) are the permutations of the first ''n'' natural numbers. The edges ident ...

of order four, with eight hexagonal faces alongside six squares that is likewise the only Archimedean solid
In geometry, an Archimedean solid is one of the 13 solids first enumerated by Archimedes. They are the convex uniform polyhedra composed of regular polygons meeting in identical vertices, excluding the five Platonic solids (which are composed ...

that can generate a honeycomb
A honeycomb is a mass of Triangular prismatic honeycomb#Hexagonal prismatic honeycomb, hexagonal prismatic Beeswax, wax cells built by honey bees in their beehive, nests to contain their larvae and stores of honey and pollen.
beekeeping, Beekee ...

on its own.
Vertex-transitive
In geometry, a polytope (e.g. a polygon or polyhedron) or a tiling is isogonal or vertex-transitive if all its vertices are equivalent under the symmetries of the figure. This implies that each vertex is surrounded by the same kinds of face in ...

semiregular polytope
In geometry, by Thorold Gosset's definition a semiregular polytope is usually taken to be a polytope that is vertex-transitive and has all its facets being regular polytopes. E.L. Elte compiled a longer list in 1912 as ''The Semiregular Polytop ...

s whose facets
A facet is a flat surface of a geometric shape, e.g., of a cut gemstone.
Facet may also refer to:
Arts, entertainment, and media
* ''Facets'' (album), an album by Jim Croce
* ''Facets'', a 1980 album by jazz pianist Monty Alexander and his tri ...

are ''finite'' exist up through the 8th dimension. In the third dimension, they include the Archimedean solids
In geometry, an Archimedean solid is one of the 13 solids first enumerated by Archimedes. They are the convex uniform polyhedra composed of regular polygons meeting in identical vertices, excluding the five Platonic solids (which are composed o ...

and the infinite family of uniform prisms and antiprism
In geometry, an antiprism or is a polyhedron composed of two parallel direct copies (not mirror images) of an polygon, connected by an alternating band of triangles. They are represented by the Conway notation .
Antiprisms are a subclass o ...

s, while in the fourth dimension, only the rectified 5-cell
In four-dimensional geometry, the rectified 5-cell is a uniform 4-polytope composed of 5 regular tetrahedral and 5 regular octahedral cells. Each edge has one tetrahedron and two octahedra. Each vertex has two tetrahedra and three octahedra. In t ...

, the rectified 600-cell
In geometry, the rectified 600-cell or rectified hexacosichoron is a convex uniform 4-polytope composed of 600 regular octahedra and 120 icosahedra cells. Each edge has two octahedra and one icosahedron. Each vertex has five octahedra and two ico ...

, and the snub 24-cell
In geometry, the snub 24-cell or snub disicositetrachoron is a convex uniform 4-polytope composed of 120 regular tetrahedral and 24 icosahedral cells. Five tetrahedra and three icosahedra meet at each vertex. In total it has 480 triangular face ...

are semiregular polytopes. For dimensions five
5 is a number, numeral, and glyph.
5, five or number 5 may also refer to:
* AD 5, the fifth year of the AD era
* 5 BC, the fifth year before the AD era
Literature
* ''5'' (visual novel), a 2008 visual novel by Ram
* ''5'' (comics), an awa ...

through eight, the demipenteract
In five-dimensional geometry, a demipenteract or 5-demicube is a semiregular 5-polytope, constructed from a ''5-hypercube'' (penteract) with alternated vertices removed.
It was discovered by Thorold Gosset. Since it was the only semiregular 5- ...

and the ktriangular prism
In geometry, a triangular prism is a three-sided prism; it is a polyhedron made of a triangular base, a translated copy, and 3 faces joining corresponding sides. A right triangular prism has rectangular sides, otherwise it is ''oblique''. A unif ...

, which is the simplest semiregular polytope that is made of three cubes and two equilateral triangles. It also includes one of only three semiregular Euclidean honeycombs: the affine
Affine may describe any of various topics concerned with connections or affinities.
It may refer to:
* Affine, a relative by marriage in law and anthropology
* Affine cipher, a special case of the more general substitution cipher
* Affine comb ...

5facets
A facet is a flat surface of a geometric shape, e.g., of a cut gemstone.
Facet may also refer to:
Arts, entertainment, and media
* ''Facets'' (album), an album by Jim Croce
* ''Facets'', a 1980 album by jazz pianist Monty Alexander and his tri ...

. The culminating figure is the ninth-dimensional 6paracompact
In mathematics, a paracompact space is a topological space in which every open cover has an open refinement that is locally finite. These spaces were introduced by . Every compact space is paracompact. Every paracompact Hausdorff space is normal, ...

hyperbolic
Hyperbolic is an adjective describing something that resembles or pertains to a hyperbola (a curve), to hyperbole (an overstatement or exaggeration), or to hyperbolic geometry.
The following phenomena are described as ''hyperbolic'' because they ...

honeycomb with infinite facets and vertex figure
In geometry, a vertex figure, broadly speaking, is the figure exposed when a corner of a polyhedron or polytope is sliced off.
Definitions
Take some corner or Vertex (geometry), vertex of a polyhedron. Mark a point somewhere along each connect ...

s in the kSphenic number
In number theory, a sphenic number (from grc, σφήνα, 'wedge') is a positive integer that is the product of three distinct prime numbers. Because there are infinitely many prime numbers, there are also infinitely many sphenic numbers.
Definit ...

s always have exactly eight divisors.
The number 8 is involved with a number of interesting mathematical phenomena related to the notion of Bott periodicity
In mathematics, the Bott periodicity theorem describes a periodicity in the homotopy groups of classical groups, discovered by , which proved to be of foundational significance for much further research, in particular in K-theory of stable comple ...

. If $O(\backslash infty)$ is the direct limit of the inclusions of real orthogonal groups $O(1)\backslash hookrightarrow\; O(2)\backslash hookrightarrow\backslash ldots\backslash hookrightarrow\; O(k)\backslash hookrightarrow\backslash ldots$, the following holds:
:$\backslash pi\_(O(\backslash infty))\backslash cong\backslash pi\_(O(\backslash infty))$.
Clifford algebras also display a periodicity of 8. For example, the algebra ''Cl''(''p'' + 8,''q'') is isomorphic to the algebra of 16 by 16 matrices with entries in ''Cl''(''p'',''q''). We also see a period of 8 in the K-theory
In mathematics, K-theory is, roughly speaking, the study of a ring generated by vector bundles over a topological space or scheme. In algebraic topology, it is a cohomology theory known as topological K-theory. In algebra and algebraic geometry, ...

of spheres and in the representation theory
Representation theory is a branch of mathematics that studies abstract algebraic structures by ''representing'' their elements as linear transformations of vector spaces, and studies modules over these abstract algebraic structures. In essen ...

of the rotation groups, the latter giving rise to the 8 by 8 spinor
In geometry and physics, spinors are elements of a complex vector space that can be associated with Euclidean space. Like geometric vectors and more general tensors, spinors transform linearly when the Euclidean space is subjected to a slight ...

ial chessboard. All of these properties are closely related to the properties of the octonion
In mathematics, the octonions are a normed division algebra over the real numbers, a kind of hypercomplex number system. The octonions are usually represented by the capital letter O, using boldface or blackboard bold \mathbb O. Octonions have e ...

s.
The spin group
In mathematics the spin group Spin(''n'') page 15 is the double cover of the special orthogonal group , such that there exists a short exact sequence of Lie groups (when )
:1 \to \mathrm_2 \to \operatorname(n) \to \operatorname(n) \to 1.
As a L ...

Spin(8) is the unique such group that exhibits the phenomenon of triality
In mathematics, triality is a relationship among three vector spaces, analogous to the duality relation between dual vector spaces. Most commonly, it describes those special features of the Dynkin diagram D4 and the associated Lie group Spin(8) ...

.
The lowest-dimensional even unimodular lattice
In geometry and mathematical group theory, a unimodular lattice is an integral lattice of determinant 1 or −1. For a lattice in ''n''-dimensional Euclidean space, this is equivalent to requiring that the volume of any fundamen ...

is the 8-dimensional $\backslash mathrm\; E\_$ lattice. Even positive definite unimodular lattices exist only in dimensions divisible by 8.
A figure 8 is the common name of a geometric
Geometry (; ) is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space such as the distance, shape, size, and relative position of figures. A mathematician who works in the field of geometry is ca ...

shape
A shape or figure is a graphics, graphical representation of an object or its external boundary, outline, or external Surface (mathematics), surface, as opposed to other properties such as color, Surface texture, texture, or material type.
A pl ...

, often used in the context of sports, such as skating. Figure-eight turns of a rope or cable around a cleat, pin, or bitt are used to belay something.
List of basic calculations

Etymology

English ''eight'', from Old English ''eahta, æhta'',Proto-Germanic
Proto-Germanic (abbreviated PGmc; also called Common Germanic) is the reconstructed proto-language of the Germanic branch of the Indo-European languages.
Proto-Germanic eventually developed from pre-Proto-Germanic into three Germanic branc ...

''*ahto''
is a direct continuation of Proto-Indo-European
Proto-Indo-European (PIE) is the reconstructed common ancestor of the Indo-European language family. Its proposed features have been derived by linguistic reconstruction from documented Indo-European languages. No direct record of Proto-Indo-E ...

'' *oḱtṓ(w)-'', and as such cognate with Greek and Latin ''octo-'', both of which stems are reflected by the English prefix oct(o)-, as in the ordinal adjective ''octaval'' or ''octavary'', the distributive adjective is ''octonary : ''For the base-8 numeral system, see octal.''
An octonary is an eight-line section in a poem, song or psalm. The most notable example is found in Psalm 119Calvin ''Bible Commentaries: Psalms, Part IV'' p287 "Some call this the octonary psalm, bec ...

''.
The adjective ''octuple'' (Latin ''octu-plus'') may also be used as a noun, meaning "a set of eight items"; the diminutive ''octuplet
A multiple birth is the culmination of one multiple pregnancy, wherein the mother gives birth to two or more babies. A term most applicable to vertebrate species, multiple births occur in most kinds of mammal
Mammals () are a group of ...

'' is mostly used to refer to eight siblings delivered in one birth.
The Semitic numeral is based on a root ''*θmn-'', whence Akkadian ''smn-'', Arabic ''ṯmn-'', Hebrew ''šmn-'' etc.
The Chinese numeral
Chinese numerals are words and characters used to denote numbers in Chinese.
Today, speakers of Chinese use three written numeral systems: the system of Arabic numerals used worldwide, and two indigenous systems. The more familiar indigenous sy ...

, written (Mandarin
Mandarin or The Mandarin may refer to:
Language
* Mandarin Chinese, branch of Chinese originally spoken in northern parts of the country
** Standard Chinese or Modern Standard Mandarin, the official language of China
** Taiwanese Mandarin, Stand ...

: ''bā''; Cantonese
Cantonese ( zh, t=廣東話, s=广东话, first=t, cy=Gwóngdūng wá) is a language within the Chinese (Sinitic) branch of the Sino-Tibetan languages originating from the city of Guangzhou (historically known as Canton) and its surrounding are ...

: ''baat''), is from Old Chinese
Old Chinese, also called Archaic Chinese in older works, is the oldest attested stage of Chinese language, Chinese, and the ancestor of all modern varieties of Chinese. The earliest examples of Chinese are divinatory inscriptions on oracle bones ...

''*priāt-'', ultimately from Sino-Tibetan ''b-r-gyat'' or ''b-g-ryat'' which also yielded Tibetan '' brgyat''.
It has been argued that, as the cardinal number
In mathematics, cardinal numbers, or cardinals for short, are a generalization of the natural numbers used to measure the cardinality (size) of sets. The cardinality of a finite set is a natural number: the number of elements in the set. Th ...

is the highest number of items that can universally be cognitively processed as a single set, the etymology of the numeral ''eight'' might be the first to be considered composite, either as "twice four" or as "two short of ten", or similar.
The Turkic words for "eight" are from a Proto-Turkic
Proto-Turkic is the linguistic reconstruction of the common ancestor of the Turkic languages that was spoken by the Proto-Turks before their divergence into the various Turkic peoples. Proto-Turkic separated into Oghur (western) and Common Turk ...

stem ''*sekiz'', which has been suggested as originating as a negation of ''eki'' "two", as in "without two fingers" (i.e., "two short of ten; two fingers are not being held up");
this same principle is found in Finnic '' *kakte-ksa'', which conveys a meaning of "two before (ten)". The Proto-Indo-European reconstruction '' *oḱtṓ(w)-'' itself has been argued as representing an old dual, which would correspond to an original meaning of "twice four".
Proponents of this "quaternary hypothesis" adduce the numeral ', which might be built on the stem ''new-'', meaning "new" (indicating the beginning of a "new set of numerals" after having counted to eight).
Evolution of the Arabic digit

The modern digit 8, like all modernArabic numerals
Arabic numerals are the ten numerical digits: , , , , , , , , and . They are the most commonly used symbols to write Decimal, decimal numbers. They are also used for writing numbers in other systems such as octal, and for writing identifiers ...

other than zero, originates with the Brahmi numerals
The Brahmi numerals are a numeral system attested from the 3rd century BCE (somewhat later in the case of most of the tens). They are a non positional decimal system. They are the direct graphic ancestors of the modern Hindu–Arabic numeral s ...

.
The Brahmi digit for ''eight'' by the 1st century was written in one stroke as a curve └┐ looking like an uppercase H with the bottom half of the left line and the upper half of the right line removed.
However, the digit for eight used in India in the early centuries of the Common Era developed considerable graphic variation, and in some cases took the shape of a single wedge, which was adopted into the Perso-Arabic tradition as ٨ (and also gave rise to the later Devanagari form ८); the alternative curved glyph also existed as a variant in Perso-Arabic tradition, where it came to look similar to our digit 5.
The digits as used in Al-Andalus
Al-Andalus DIN 31635, translit. ; an, al-Andalus; ast, al-Ándalus; eu, al-Andalus; ber, ⴰⵏⴷⴰⵍⵓⵙ, label=Berber languages, Berber, translit=Andalus; ca, al-Àndalus; gl, al-Andalus; oc, Al Andalús; pt, al-Ândalus; es, ...

by the 10th century were a distinctive western variant of the glyphs used in the Arabic-speaking world, known as ''ghubār'' numerals (''ghubār'' translating to "sand table
A sand table uses constrained sand for modelling or educational purposes. The original version of a sand table may be the abax used by early Greek students. In the modern era, one common use for a sand table is to make terrain models for milita ...

"). In these digits, the line of the ''5''-like glyph used in Indian manuscripts for eight came to be formed in ghubār as a closed loop, which was the ''8''-shape that became adopted into European use in the 10th century.
Just as in most modern typeface
A typeface (or font family) is the design of lettering that can include variations in size, weight (e.g. bold), slope (e.g. italic), width (e.g. condensed), and so on. Each of these variations of the typeface is a font.
There are list of type ...

s, in typefaces with text figures
Text figures (also known as non-lining, lowercase, old style, ranging, hanging, medieval, billing, or antique figures or numerals) are numerals designed with varying heights in a fashion that resembles a typical line of running text, hence the ...

the character for the digit 8 usually has an ascender, as, for example, in .
The infinity symbol
The infinity symbol (\infty) is a mathematical symbol representing the concept of infinity. This symbol is also called a lemniscate, after the lemniscate curves of a similar shape studied in algebraic geometry, or "lazy eight", in the terminol ...

∞, described as a "sideways figure eight", is unrelated to the digit 8 in origin; it is first used (in the mathematical meaning "infinity") in the 17th century, and it may be derived from the Roman numeral
Roman numerals are a numeral system that originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. Numbers are written with combinations of letters from the Latin alphabet, eac ...

for "one thousand" CIƆ, or alternatively from the final Greek letter, ω.
In science

Physics

* In nuclear physics, the second magic number. * Inparticle physics
Particle physics or high energy physics is the study of fundamental particles and forces that constitute matter and radiation. The fundamental particles in the universe are classified in the Standard Model as fermions (matter particles) an ...

, the eightfold way is used to classify sub-atomic particles.
* In statistical mechanics
In physics, statistical mechanics is a mathematical framework that applies statistical methods and probability theory to large assemblies of microscopic entities. It does not assume or postulate any natural laws, but explains the macroscopic be ...

, the eight-vertex model
In statistical mechanics, the eight-vertex model is a generalisation of the ice-type (six-vertex) models; it was discussed by Sutherland, and Fan & Wu, and solved by Baxter in the zero-field case.
Description
As with the ice-type models, the ei ...

has 8 possible configurations of arrows at each vertex.
Astronomy

*Messier object
The Messier objects are a set of 110 astronomical objects catalogued by the French astronomer Charles Messier in his ''Catalogue des Nébuleuses et des Amas d'Étoiles'' (''Catalogue of Nebulae and Star Clusters'').
Because Messier was only int ...

M8, a magnitude 5.0 nebula
A nebula ('cloud' or 'fog' in Latin; pl. nebulae, nebulæ or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral or molecular hydrogen and also cosmic dust. Nebulae are often star-forming regio ...

in the constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object.
The origins of the e ...

of Sagittarius.
* The New General Catalogue
The ''New General Catalogue of Nebulae and Clusters of Stars'' (abbreviated NGC) is an astronomical catalogue of deep-sky objects compiled by John Louis Emil Dreyer in 1888. The NGC contains 7,840 objects, including galaxies, star clusters and ...

br>objectNGC 8
NGC 8 is an asterism of two completely unrelated stars (spectral types K6I and G4) in the constellation Pegasus, discovered on 29 September 1865 by Otto Wilhelm von Struve. It is approximately 2.7 arc minutes away from NGC 9.
The two sta ...

, a double star in the constellation Pegasus
Pegasus ( grc-gre, Πήγασος, Pḗgasos; la, Pegasus, Pegasos) is one of the best known creatures in Greek mythology. He is a winged divine stallion usually depicted as pure white in color. He was sired by Poseidon, in his role as hor ...

.
* Since the demotion of Pluto
Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the S ...

to a dwarf planet
A dwarf planet is a small planetary-mass object that is in direct orbit of the Sun, smaller than any of the eight classical planets but still a world in its own right. The prototypical dwarf planet is Pluto. The interest of dwarf planets to p ...

on 24 August 2006, in our Solar System
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...

, eight of the bodies orbiting the Sun are considered to be planet
A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...

s.
Chemistry

* Theatomic number
The atomic number or nuclear charge number (symbol ''Z'') of a chemical element is the charge number of an atomic nucleus. For ordinary nuclei, this is equal to the proton number (''n''p) or the number of protons found in the nucleus of every ...

of oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

.
* The most stable allotrope of a sulfur
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...

molecule is made of eight sulfur atoms arranged in a rhombic form.
* The maximum number of electrons that can occupy a valence shell
In chemistry and physics, a valence electron is an electron in the outer shell associated with an atom, and that can participate in the formation of a chemical bond if the outer shell is not closed. In a single covalent bond, a shared pair forms ...

.
* The red pigment lycopene
Lycopene is an organic compound classified as a tetraterpene and a carotene. Lycopene (from the neo-Latin ''Lycopersicum'', the tomato species) is a bright red carotenoid hydrocarbon found in tomatoes and other red fruits and vegetables.
Occu ...

consists of eight isoprene
Isoprene, or 2-methyl-1,3-butadiene, is a common volatile organic compound with the formula CH2=C(CH3)−CH=CH2. In its pure form it is a colorless volatile liquid. Isoprene is an unsaturated hydrocarbon. It is produced by many plants and animals ...

units.
Geology

* Adisphenoid
In geometry, a disphenoid () is a tetrahedron whose four faces are congruent acute-angled triangles. It can also be described as a tetrahedron in which every two edges that are opposite each other have equal lengths. Other names for the same sh ...

crystal is bounded by eight scalene triangles arranged in pairs. A ditetragonal prism in the tetragonal crystal system
In crystallography, the tetragonal crystal system is one of the 7 crystal systems. Tetragonal crystal lattices result from stretching a cubic lattice along one of its lattice vectors, so that the cube becomes a rectangular prism with a square ...

has eight similar faces whose alternate interfacial angles only are equal.
Biology

* Allspider
Spiders ( order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species ...

s, and more generally all arachnid
Arachnida () is a class of joint-legged invertebrate animals (arthropods), in the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, harvestmen, camel spiders, whip spiders and vinegaroon ...

s, have eight legs. Orb-weaver spider
Orb-weaver spiders are members of the spider family Araneidae. They are the most common group of builders of spiral wheel-shaped webs often found in gardens, fields, and forests. The English word "orb" can mean "circular", hence the English name ...

s of the cosmopolitan family Areneidae have eight similar eyes.
* The octopus
An octopus ( : octopuses or octopodes, see below for variants) is a soft-bodied, eight- limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttle ...

and its cephalopod relatives in genus ''Argonauta'' have eight arms (tentacles).
* Compound coelenterates of the subclass or order Alcyonaria
Octocorallia (also known as Alcyonaria) is a class of Anthozoa comprising around 3,000 species of water-based organisms formed of colonial polyps with 8-fold symmetry. It includes the blue coral, soft corals, sea pens, and gorgonians (sea fans ...

have polyps with eight-branched tentacles and eight septa.
* Sea anemones of genus ''Edwardsia
''Edwardsia'' is a genus of sea anemones, the type of the family Edwardsiidae. They have eight mesenteries and live in tubes in the sand. The name, in New Latin, commemorates the French zoologist Henri Milne-Edwards
Henri Milne-Edwards (23 O ...

'' have eight mesenteries
In zoology, a mesentery is a membrane inside the body cavity of an animal. The term identifies different structures in different phyla: in vertebrates it is a double fold of the peritoneum enclosing the intestines; in other organisms it forms co ...

.
* Animals of phylum Ctenophora
Ctenophora (; ctenophore ; ) comprise a phylum of marine invertebrates, commonly known as comb jellies, that inhabit sea waters worldwide. They are notable for the groups of cilia they use for swimming (commonly referred to as "combs"), an ...

swim by means of eight meridional bands of transverse ciliated plates, each plate representing a row of large modified cilia.
* The eight-spotted forester (genus ''Alypia'', family Zygaenidae
The Zygaenidae moths are a family of Lepidoptera. The majority of zygaenids are tropical, but they are nevertheless quite well represented in temperate regions. Some of the 1000 or so species are commonly known as burnet or forester moths, oft ...

) is a diurnal moth having black wings with brilliant white spots.
* The ascus
An ascus (; ) is the sexual spore-bearing cell produced in ascomycete fungi. Each ascus usually contains eight ascospores (or octad), produced by meiosis followed, in most species, by a mitotic cell division. However, asci in some genera or s ...

in fungi of the class Ascomycetes
Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. It is the largest phylum of Fungi, with over 64,000 species. The defi ...

, following nuclear fusion, bears within it typically eight ascospores.
* Herbs of genus ''Coreopsis
''Coreopsis'' () is a genus of flowering plants in the family Asteraceae. Common names include calliopsis and tickseed, a name shared with various other plants.
Description
These plants range from in height. The flowers are usually yellow wi ...

'' (tickseed) have showy flower heads with involucral bracts in two distinct series of eight each.
* In human adult dentition
Permanent teeth or adult teeth are the second set of teeth formed in diphyodont mammals. In humans and old world simians, there are thirty-two permanent teeth, consisting of six maxillary and six mandibular molars, four maxillary and four mandibu ...

there are eight teeth in each quadrant. The eighth tooth is the so-called wisdom tooth
A third molar, commonly called wisdom tooth, is one of the three molars per quadrant of the human dentition. It is the most posterior of the three. The age at which wisdom teeth come through ( erupt) is variable, but this generally occurs betwe ...

.
* There are eight cervical nerves
A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into the ...

on each side in man and most mammals.
Psychology

* There are eightJungian cognitive functions
Cognitive functions, also referred to as psychological functions, as described by Carl Jung in his book ''Psychological Types'', are particular mental processes within a person's psyche that are present regardless of common circumstance. This is a ...

, according to the MBTI models by John Beebe
John Beebe (born June 24, 1939) is an American psychiatrist and Jungian analyst in practice in San Francisco.
Beebe was born in Washington, D.C. He received degrees from Harvard College and the University of Chicago medical school. He is a pas ...

and Linda Berens
Linda may refer to:
As a name
* Linda (given name), a female given name (including a list of people and fictional characters so named)
* Linda (singer) (born 1977), stage name of Svetlana Geiman, a Russian singer
* Anita Linda (born Alice Lake ...

.
* Timothy Leary
Timothy Francis Leary (October 22, 1920 – May 31, 1996) was an American psychologist and author known for his strong advocacy of psychedelic drugs. Evaluations of Leary are polarized, ranging from bold oracle to publicity hound. He was "a her ...

identified a hierarchy of eight levels of consciousness.
In technology

* Abyte
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit ...

is eight bit
The bit is the most basic unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represente ...

s.
* Many (mostly historic) computer architectures are eight-bit, among them the Nintendo Entertainment System
The Nintendo Entertainment System (NES) is an 8-bit third-generation home video game console produced by Nintendo. It was first released in Japan in 1983 as the commonly known as the The NES, a redesigned version, was released in America ...

.
* Standard-8 and Super-8
Super 8 mm film is a motion-picture film format released in 1965 by Eastman Kodak as an improvement over the older "Double" or "Regular" 8 mm home movie format.
The film is nominally 8 mm wide, the same as older formatted 8& ...

are 8 mm film formats
A film format is a technical definition of a set of standard characteristics regarding image capture on photographic film for still images or film stock for filmmaking. It can also apply to projected film, either slides or movies. The primary ...

.
* Video8, Hi8 and Digital8 are related 8 mm video format
The 8mm video format refers informally to three related videocassette formats. These are the original Video8 (analog recording) format and its improved successor Hi8 (analog video and analog audio but with provision for digital audio), as well as ...

s.
* On most phones, the 8 key is associated with the letters T, U, and V, but on the BlackBerry Pearl it is the key for B and N.
* An eight may refer to an eight-cylinder engine or automobile. A V8 engine
A V8 engine is an eight-cylinder piston engine in which two banks of four cylinders share a common crankshaft and are arranged in a V configuration.
The first V8 engine was produced by the French Antoinette company in 1904, developed and us ...

is an internal combustion engine
An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combus ...

with eight cylinders configured in two banks (rows) of four forming a "V" when seen from the end.
* A figure-eight knot
The figure-eight knot or figure-of-eight knot is a type of stopper knot. It is very important in both sailing and rock climbing as a method of stopping ropes from running out of retaining devices. Like the overhand knot, which will jam under st ...

(so named for its configuration) is a kind of stopper knot
Stopper may refer to:
* Bung, a plug used to stop the opening of a container
** Laboratory rubber stopper, a specific type of bung
* Plug (sanitation), used to stop a drainage outlet
* Defender (association football), in soccer (association footba ...

.
* The number eight written in parentheses is the code for the musical note in Windows Live Messenger
MSN Messenger (also known colloquially simply as "Messenger"), later rebranded as Windows Live Messenger, was a cross-platform instant messaging client, instant-messaging client developed by Microsoft. It connected to the Microsoft Messenger ser ...

.
* In a seven-segment display
A seven-segment display is a form of electronic display device for displaying decimal numerals that is an alternative to the more complex dot matrix displays.
Seven-segment displays are widely used in digital clocks, electronic meters, basic ...

, when an 8 is illuminated, all the display bulbs are on.
In measurement

* TheSI prefix
The International System of Units, known by the international abbreviation SI in all languages and sometimes pleonastically as the SI system, is the modern form of the metric system and the world's most widely used system of measurement. E ...

for 1000United States customary units
United States customary units form a system of measurement units commonly used in the United States and U.S. territories since being standardized and adopted in 1832. The United States customary system (USCS or USC) developed from English units ...

), there are eight fluid ounce
A fluid ounce (abbreviated fl oz, fl. oz. or oz. fl., old forms ℥, fl ℥, f℥, ƒ ℥) is a unit of volume (also called ''capacity'') typically used for measuring liquids. The British Imperial, the United States customary, and the United St ...

s in a cup
A cup is an open-top used to hold hot or cold liquids for pouring or drinking; while mainly used for drinking, it also can be used to store solids for pouring (e.g., sugar, flour, grains, salt). Cups may be made of glass, metal, china, clay, ...

, eight pint
The pint (, ; symbol pt, sometimes abbreviated as ''p'') is a unit of volume or capacity in both the imperial unit, imperial and United States customary units, United States customary measurement systems. In both of those systems it is tradition ...

s in a gallon
The gallon is a unit of volume in imperial units and United States customary units. Three different versions are in current use:
*the imperial gallon (imp gal), defined as , which is or was used in the United Kingdom, Ireland, Canada, Austral ...

and eight tablespoon
A tablespoon (tbsp. , Tbsp. , Tb. , or T.) is a large spoon. In many English-speaking regions, the term now refers to a large spoon used for serving; however, in some regions, it is the largest type of spoon used for eating.
By extension, the ter ...

fuls in a gill
A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

.
* There are eight furlong
A furlong is a measure of distance in imperial units and United States customary units equal to one eighth of a mile, equivalent to 660 feet, 220 yards, 40 rods, 10 chains or approximately 201 metres. It is now mostly confined to use in hors ...

s in a mile.
* The clove, an old English unit
English units are the units of measurement used in England up to 1826 (when they were replaced by Imperial units), which evolved as a combination of the Anglo-Saxon and Roman systems of units. Various standards have applied to English units at d ...

of weight, was equal to eight pounds when measuring cheese.
* An eight may be an article of clothing of the eighth size
Size in general is the Magnitude (mathematics), magnitude or dimensions of a thing. More specifically, ''geometrical size'' (or ''spatial size'') can refer to linear dimensions (length, width, height, diameter, perimeter), area, or volume ...

.
* Force eight is the first wind
Wind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few hou ...

strength attributed to a gale
A gale is a strong wind; the word is typically used as a descriptor in nautical contexts. The U.S. National Weather Service defines a gale as sustained surface winds moving at a speed of between 34 and 47 knots (, or ).Beaufort scale
The Beaufort scale is an empirical measure that relates wind speed to observed conditions at sea or on land. Its full name is the Beaufort wind force scale.
History
The scale was devised in 1805 by the Irish hydrographer Francis Beaufort ...

when announced on a Shipping Forecast
The Shipping Forecast is a BBC Radio broadcast of weather reports and forecasts for the seas around the coasts of the British Isles. It is produced by the Met Office and broadcast by BBC Radio 4 on behalf of the Maritime and Coastguard Agency. ...

.
In culture

Currency

* Sailors and civilians alike from the 1500s onward referred to evenly divided parts of theSpanish dollar
The Spanish dollar, also known as the piece of eight ( es, Real de a ocho, , , or ), is a silver coin of approximately diameter worth eight Spanish reales. It was minted in the Spanish Empire following a monetary reform in 1497 with content ...

as "pieces of eight", or "bits".
Architecture

* Various types of buildings are usually eight-sided (octagonal), such as single-roomedgazebo
A gazebo is a pavilion structure, sometimes octagonal or turret-shaped, often built in a park, garden or spacious public area. Some are used on occasions as bandstands.
Etymology
The etymology given by Oxford Dictionaries (website), Oxford D ...

s and multi-roomed pagoda
A pagoda is an Asian tiered tower with multiple eaves common to Nepal, India, China, Japan, Korea, Myanmar, Vietnam, and other parts of Asia. Most pagodas were built to have a religious function, most often Buddhist but sometimes Taoist, ...

s (descended from stupas; see religion section below).
* Eight caulicoles rise out of the leafage in a Corinthian capital
The Corinthian order (Greek: Κορινθιακός ρυθμός, Latin: ''Ordo Corinthius'') is the last developed of the three principal classical orders of Ancient Greek architecture and Roman architecture. The other two are the Doric order w ...

, ending in leaves that support the volutes
A volute is a spiral, scroll-like ornament that forms the basis of the Ionic order, found in the capital of the Ionic column. It was later incorporated into Corinthian order and Composite column capitals. Four are normally to be found on an ...

.
In religion, folk belief and divination

Hinduism

* Also known as Ashtha, Aṣṭa, or Ashta inSanskrit
Sanskrit (; attributively , ; nominally , , ) is a classical language belonging to the Indo-Aryan branch of the Indo-European languages. It arose in South Asia after its predecessor languages had diffused there from the northwest in the late ...

, it is the number of wealth and abundance.
* The goddess of wealth and prosperity, Lakshmi
Lakshmi (; , sometimes spelled Laxmi, ), also known as Shri (, ), is one of the principal goddesses in Hinduism. She is the goddess of wealth, fortune, power, beauty, fertility and prosperity, and associated with ''Maya'' ("Illusion"). Alo ...

, has eight forms known as Ashta Lakshmi
Ashta Lakshmi (Sanskrit: अष्टलक्ष्मी, IAST: Aṣṭalakṣmī; lit. "Octet of Lakshmi") or Ashtalakshmi, is a group of the eight manifestations of Lakshmi, the Hindu goddess of prosperity. She presides over eight sources of ...

and worshipped as: "''Maha-lakshmi, Dhana-lakshmi, Dhanya-lakshmi, Gaja-lakshmi,

Santana-lakshmi, Veera-lakshmi, Vijaya-lakshmi and Vidhya-lakshmi''" *There are eight ''nidhi'', or seats of wealth, according to

Hinduism
Hinduism () is an Indian religion or '' dharma'', a religious and universal order or way of life by which followers abide. As a religion, it is the world's third-largest, with over 1.2–1.35 billion followers, or 15–16% of the global p ...

.
*There are eight guardians of the directions
The Guardians of the Directions (Sanskrit: दिक्पाल, Dikpāla) are the deities who rule the specific directions of space according to Hinduism, Jainism and '' '' Buddhism—especially . As a group of eight deities, they are called ( ...

known as ''Astha-dikpalas''.
*There are eight Hindu
Hindus (; ) are people who religiously adhere to Hinduism.Jeffery D. Long (2007), A Vision for Hinduism, IB Tauris, , pages 35–37 Historically, the term has also been used as a geographical, cultural, and later religious identifier for ...

monasteries established by the saint Madhvacharya
Madhvacharya (; ; CE 1199-1278 or CE 1238–1317), sometimes Anglicisation, anglicised as Madhva Acharya, and also known as Purna Prajna () and Ānanda Tīrtha, was an Indian philosopher, theologian and the chief proponent of the ''Dvaita'' ...

in Udupi
Udupi (alternate spelling Udipi; also known as Odipu) is a city in the Indian state of Karnataka. Udupi is situated about north of the educational, commercial and industrial hub of Mangalore and about west of state capital Bangalore by road.
...

, India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

popularly known as the ''Ashta Mathas of Udupi
The Tulu Ashta Mathas of Udupi ( kn, ಉಡುಪಿಯ ತುಳು ಅಷ್ಟ ಮಠಗಳು) are a group of eight ''mathas'' or Hindu monasteries established by Madhvacharya, the preceptor of the Dvaita school of Hindu thought with his di ...

''.
Buddhism

* TheDharmacakra
The dharmachakra (Sanskrit: धर्मचक्र; Pali: ''dhammacakka'') or wheel of dharma is a widespread symbol used in Indian religions such as Hinduism, Jainism, and especially Buddhism.John C. Huntington, Dina Bangdel, ''The Circle o ...

, a Buddhist
Buddhism ( , ), also known as Buddha Dharma and Dharmavinaya (), is an Indian religion or philosophical tradition based on teachings attributed to the Buddha. It originated in northern India as a -movement in the 5th century BCE, and ...

symbol, has eight spokes. The Buddha's principal teaching—the Four Noble Truths
In Buddhism, the Four Noble Truths (Sanskrit: ; pi, cattāri ariyasaccāni; "The four Arya satyas") are "the truths of the Noble Ones", the truths or realities for the "spiritually worthy ones".

—ramifies as the Noble Eightfold Path">Four Noble Truths: BUDDHIST PHILOSOPHY Encycl ...Yogacara
Yogachara ( sa, योगाचार, IAST: '; literally "yoga practice"; "one whose practice is yoga") is an influential tradition of Buddhist philosophy and psychology emphasizing the study of cognition, perception, and consciousness through t ...

school of thought: consciousness in the five senses, thought-consciousness, self-consciousness, and unconsciousness-"consciousness" or "store-house consciousness" (alaya-vijñana). The "irreversible" state of enlightenment, at which point a Bodhisattva goes on "autopilot", is the Eight Ground or ''bhūmi''. In general, "eight" seems to be an auspicious number for Buddhists, e.g., the "eight auspicious symbols" (the jewel-encrusted parasol; the goldfish (always shown as a pair, e.g., the glyph of Pisces); the self-replenishing amphora; the white ''kamala'' lotus-flower; the white conch; the eternal (Celtic-style, infinitely looping) knot; the banner of imperial victory; the eight-spoked wheel that guides the ship of state, or that symbolizes the Buddha's teaching). Similarly, Buddha's birthday
Buddha's Birthday (also known as Buddha Jayanti, also known as his day of enlightenment – Buddha Purnima, Buddha Pournami) is a Buddhist festival that is celebrated in most of East Asia and South Asia commemorating the birth of the Gautama ...

falls on the 8th day of the 4th month of the Chinese calendar
The traditional Chinese calendar (also known as the Agricultural Calendar 曆; 农历; ''Nónglì''; 'farming calendar' Former Calendar 曆; 旧历; ''Jiùlì'' Traditional Calendar 曆; 老历; ''Lǎolì'', is a lunisolar calendar ...

.
Judaism

* The religious rite ofbrit milah
The ''brit milah'' ( he, בְּרִית מִילָה ''bərīṯ mīlā'', ; Ashkenazi Hebrew, Ashkenazi pronunciation: , "Covenant (religion), covenant of circumcision"; Yiddish pronunciation: ''bris'' ) is Religion and circumcision, the cerem ...

(commonly known as circumcision
Circumcision is a surgical procedure, procedure that removes the foreskin from the human penis. In the most common form of the operation, the foreskin is extended with forceps, then a circumcision device may be placed, after which the foreskin ...

) is held on a baby boy's eighth day of life.
* Hanukkah
or English translation: 'Establishing' or 'Dedication' (of the Temple in Jerusalem)
, nickname =
, observedby = Jews
, begins = 25 Kislev
, ends = 2 Tevet or 3 Tevet
, celebrations = Lighting candles each night. ...

is an eight-day Jewish holiday that starts on the 25th day of Kislev
Kislev or Chislev (Hebrew: כִּסְלֵו, Standard ''Kīslev'' Tiberian ''Kīslēw''), also 'Chisleu' in the King James (authorized English) Bible, is the third month of the civil year and the ninth month of the ecclesiastical year on the Heb ...

.
* Shemini Atzeret
Shemini Atzeret (—"Eighth

(ay of
Ay, AY or variants, may refer to:
People
* Ay (pharaoh), a pharaoh of the 18th Egyptian dynasty
* Merneferre Ay, a pharaoh of the 13th Egyptian dynasty
* A.Y. (musician) (born 1981), a Tanzanian "bongo flava" artist
* A.Y, stage name of Ayo Makun ...

Assembly") is a Jewish holidays, Jewish holiday. It is celebrated on the 22nd day of the Hebrew calendar, Hebrew month of Tishrei in the Land of Israel, and on the 22nd and 23rd outside the Land, usually coi ...Hebrew
Hebrew (; ; ) is a Northwest Semitic language of the Afroasiatic language family. Historically, it is one of the spoken languages of the Israelites and their longest-surviving descendants, the Jews and Samaritans. It was largely preserved ...

: "Eighth Day of Assembly") is a one-day Jewish holiday immediately following the seven-day holiday of Sukkot
or ("Booths, Tabernacles")
, observedby = Jews, Samaritans, a few Protestant denominations, Messianic Jews, Semitic Neopagans
, type = Jewish, Samaritan
, begins = 15th day of Tishrei
, ends = 21st day of Tishre ...

.
Christianity

* The spiritual Eighth Day, because the number 7 refers to the days of the week (which repeat themselves). * The number ofBeatitudes
The Beatitudes are sayings attributed to Jesus, and in particular eight blessings recounted by Jesus in the Sermon on the Mount in the Gospel of Matthew, and four in the Sermon on the Plain in the Gospel of Luke, followed by four woes which mirr ...

.
* 1 Peter 3:20 states that there were eight people on Noah's Ark
Noah's Ark ( he, תיבת נח; Biblical Hebrew: ''Tevat Noaḥ'')The word "ark" in modern English comes from Old English ''aerca'', meaning a chest or box. (See Cresswell 2010, p.22) The Hebrew word for the vessel, ''teva'', occurs twice in t ...

.
* The Antichrist
In Christian eschatology, the Antichrist refers to people prophesied by the Bible to oppose Jesus Christ and substitute themselves in Christ's place before the Second Coming. The term Antichrist (including one plural form) 1 John ; . 2 John . ...

is the eighth king in the Book of Revelation
The Book of Revelation is the final book of the New Testament (and consequently the final book of the Christian Bible). Its title is derived from the first word of the Koine Greek text: , meaning "unveiling" or "revelation". The Book of R ...

.
Islam

* InIslam
Islam (; ar, ۘالِإسلَام, , ) is an Abrahamic religions, Abrahamic Monotheism#Islam, monotheistic religion centred primarily around the Quran, a religious text considered by Muslims to be the direct word of God in Islam, God (or ...

, eight is the number of angel
In various theistic religious traditions an angel is a supernatural spiritual being who serves God.
Abrahamic religions often depict angels as benevolent celestial intermediaries between God (or Heaven) and humanity. Other roles include ...

s carrying the throne
A throne is the seat of state of a potentate or dignitary, especially the seat occupied by a sovereign on state occasions; or the seat occupied by a pope or bishop on ceremonial occasions. "Throne" in an abstract sense can also refer to the monar ...

of Allah
Allah (; ar, الله, translit=Allāh, ) is the common Arabic word for God. In the English language, the word generally refers to God in Islam. The word is thought to be derived by contraction from '' al- ilāh'', which means "the god", an ...

in heaven.
* The number of gates of heaven
Taoism

*Ba Gua
The bagua or pakua (八卦) are a set of eight symbols that originated in China, used in Taoist cosmology to represent the fundamental principles of reality, seen as a range of eight interrelated concepts. Each consists of three lines, each lin ...

* Ba Xian
The Eight Immortals () are a group of legendary '' xian'' ("immortals") in Chinese mythology. Each immortal's power can be transferred to a vessel () that can bestow life or destroy evil. Together, these eight vessels are called the "Covert Eight ...

* Ba Duan Jin
Other

* InWicca
Wicca () is a modern Pagan religion. Scholars of religion categorise it as both a new religious movement and as part of the occultist stream of Western esotericism. It was developed in England during the first half of the 20th century and was ...

, there are eight Sabbats, festivals, seasons, or spokes in the Wheel of the Year
The Wheel of the Year is an annual cycle of seasonal festivals, observed by many modern pagans, consisting of the year's chief solar events (solstices and equinoxes) and the midpoints between them. While names for each festival vary among dive ...

.
* In Ancient Egyptian mythology
Egyptian mythology is the collection of myths from ancient Egypt, which describe the actions of the Egyptian gods as a means of understanding the world around them. The beliefs that these myths express are an important part of ancient Egyptia ...

, the Ogdoad represents the eight primordial deities of creation.
* In Scientology
Scientology is a set of beliefs and practices invented by American author L. Ron Hubbard, and an associated movement. It has been variously defined as a cult, a business, or a new religious movement. The most recent published census data indi ...

there are eight dynamics of existence.
* There is also the Ogdoad in Gnosticism
Gnosticism (from grc, γνωστικός, gnōstikós, , 'having knowledge') is a collection of religious ideas and systems which coalesced in the late 1st century AD among Jewish
Jews ( he, יְהוּדִים, , ) or Jewish people ...

.
As a lucky number

* The number eight is considered to be a lucky number in Chinese and other Asian cultures. Eight (;accounting
Accounting, also known as accountancy, is the measurement, processing, and communication of financial and non financial information about economic entities such as businesses and corporations. Accounting, which has been called the "languag ...

; pinyin
Hanyu Pinyin (), often shortened to just pinyin, is the official romanization system for Standard Mandarin Chinese in China, and to some extent, in Singapore and Malaysia. It is often used to teach Mandarin, normally written in Chinese for ...

''bā'') is considered a lucky number in Chinese culture because it sounds like the word meaning to generate wealth (; Pinyin
Hanyu Pinyin (), often shortened to just pinyin, is the official romanization system for Standard Mandarin Chinese in China, and to some extent, in Singapore and Malaysia. It is often used to teach Mandarin, normally written in Chinese for ...

: ''fā''). Property with the number 8 may be valued greatly by Chinese. For example, a Hong Kong number plate
A vehicle registration plate, also known as a number plate (British English), license plate (American English), or licence plate (Canadian English), is a metal or plastic plate attached to a motor vehicle or trailer for official identificatio ...

with the number 8 was sold for $640,000. The opening ceremony of the Summer Olympics in Beijing started at 8 seconds and 8 minutes past 8 pm (local time) on 8 August 2008.
* In Pythagorean numerology
Numerology (also known as arithmancy) is the belief in an occult, divine or mystical relationship between a number and one or more coinciding events. It is also the study of the numerical value, via an alphanumeric system, of the letters in ...

(a pseudoscience
Pseudoscience consists of statements, beliefs, or practices that claim to be both scientific and factual but are incompatible with the scientific method. Pseudoscience is often characterized by contradictory, exaggerated or falsifiability, unfa ...

) the number 8 represents victory, prosperity and overcoming.
* is also considered a lucky number in Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

, but the reason is different from that in Chinese culture. Eight gives an idea of growing prosperous, because the letter () broadens gradually.
* The Japanese thought of as a holy number in the ancient times. The reason is less well-understood, but it is thought that it is related to the fact they used eight to express large numbers vaguely such as (literally, eightfold and twentyfold), (literally, eight clouds), (literally, eight millions of Gods), etc. It is also guessed that the ancient Japanese gave importance to pairs, so some researchers guess twice as , which is also guessed to be a holy number in those times because it indicates the world (north, south, east, and west) might be considered a very holy number.
* In numerology
Numerology (also known as arithmancy) is the belief in an occult, divine or mystical relationship between a number and one or more coinciding events. It is also the study of the numerical value, via an alphanumeric system, of the letters in ...

, 8 is the number of building, and in some theories, also the number of destruction.
In astrology

* Inastrology
Astrology is a range of Divination, divinatory practices, recognized as pseudoscientific since the 18th century, that claim to discern information about human affairs and terrestrial events by studying the apparent positions of Celestial o ...

, Scorpio is the 8th astrological sign
In Western astrology, astrological signs are the twelve 30-degree sectors that make up Earth's 360-degree orbit around the Sun. The signs enumerate from the first day of spring, known as the First Point of Aries, which is the vernal equinox. ...

of the Zodiac
The zodiac is a belt-shaped region of the sky that extends approximately 8° north or south (as measured in celestial latitude) of the ecliptic, the Sun path, apparent path of the Sun across the celestial sphere over the course of the year. ...

.
* In the Middle Ages
In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire a ...

, 8 was the number of "unmoving" stars in the sky, and symbolized the perfection of incoming planetary energy.
In music and dance

* A note played for one-eighth the duration of a whole note is called aneighth note
180px, Figure 1. An eighth note with stem extending up, an eighth note with stem extending down, and an eighth rest.
180px, Figure 2. Four eighth notes beamed together.
An eighth note (American) or a quaver (British) is a musical note play ...

, or quaver.
* An octave
In music, an octave ( la, octavus: eighth) or perfect octave (sometimes called the diapason) is the interval between one musical pitch and another with double its frequency. The octave relationship is a natural phenomenon that has been refer ...

, the interval between two musical note
In music, a note is the representation of a musical sound.
Notes can represent the Pitch (music), pitch and Duration (music), duration of a sound in musical notation. A note can also represent a pitch class.
Notes are the building blocks of much ...

s with the same letter name (where one has double the frequency of the other), is so called because there are eight notes between the two on a standard major or minor diatonic scale
In music theory, a diatonic scale is any heptatonic scale that includes five whole steps (whole tones) and two half steps (semitones) in each octave, in which the two half steps are separated from each other by either two or three whole steps, ...

, including the notes themselves and without chromatic deviation. The ecclesiastical modes
Mode ( la, modus meaning "manner, tune, measure, due measure, rhythm, melody") may refer to:
Arts and entertainment
* '' MO''D''E (magazine)'', a defunct U.S. women's fashion magazine
* ''Mode'' magazine, a fictional fashion magazine which is ...

are ascending diatonic musical scales of eight notes or tones comprising an octave.
* There are eight notes in the octatonic scale
An octatonic scale is any eight-note musical scale. However, the term most often refers to the symmetric scale composed of alternating whole and half steps, as shown at right. In classical theory (in contrast to jazz theory), this symmetrical ...

.
* There are eight musicians in a double quartet or an octet
Octet may refer to:
Music
* Octet (music), ensemble consisting of eight instruments or voices, or composition written for such an ensemble
** String octet, a piece of music written for eight string instruments
*** Octet (Mendelssohn), 1825 compos ...

. Both terms may also refer to a musical composition for eight voices or instruments.
* Caledonians is a square dance for eight, resembling the quadrille
The quadrille is a dance that was fashionable in late 18th- and 19th-century Europe and its colonies. The quadrille consists of a chain of four to six '' contredanses''. Latterly the quadrille was frequently danced to a medley of opera melodie ...

.
* Album
An album is a collection of audio recordings issued on compact disc (CD), Phonograph record, vinyl, audio tape, or another medium such as Digital distribution#Music, digital distribution. Albums of recorded sound were developed in the early ...

s with the number eight in their title include ''8'' by the Swedish band Arvingarna
Arvingarna is a Swedish dansband formed in Gothenburg in 1989. The group consists of Casper Janebrink (vocals and bass guitar), Lars Larsson (guitars, vocals and keyboards), Kim Carlsson (vocals and guitars) and Tommy Carlsson (drums and vocals). ...

, '' 8'' by the American rock band Incubus
An incubus is a demon in male form in folklore that seeks to have sexual intercourse with sleeping women; the corresponding spirit in female form is called a succubus. In medieval Europe, union with an incubus was supposed by some to result in t ...

, ''The Meaning of 8
''The Meaning of 8'' is the seventh studio album by the experimental indie rock band Cloud Cult
Cloud Cult is an experimental indie rock band from St. Cloud, Minnesota, United States, led by singer-songwriter Craig Minowa. The name originated ...

'' by Minnesota indie rock band Cloud Cult
Cloud Cult is an experimental indie rock band from St. Cloud, Minnesota, United States, led by singer-songwriter Craig Minowa. The name originated from the ancient prophecies of indigenous North Americans.
History
Cloud Cult developed in 1995 ...

and ''8ight'' by Anglo-American singer-songwriter Beatie Wolfe
Beatie Wolfe is an Anglo-American award-winning, multimedia artist and musician described as a "musical weirdo and visionary" known for seeing music differently and creating new formats for music and art in the digital era. These projects inclu ...

.
* Dream Theater
Dream Theater is an American progressive metal band formed in 1985 under the name Majesty by John Petrucci, John Myung and Mike Portnoy while they attended Berklee College of Music in Boston, Massachusetts. They subsequently dropped out of the ...

's eighth album ''Octavarium
''Octavarium'' is the eighth studio album by American progressive metal band Dream Theater. Released on June 7, 2005, it was the band's final release with Atlantic Records. Recorded between September 2004 and February 2005, it was the last albu ...

'' contains many different references to the number 8, including the number of songs and various aspects of the music and cover artwork.
* "Eight maids a-milking" is the gift on the eighth day of Christmas in the carol "The Twelve Days of Christmas (song), The Twelve Days of Christmas".
* The 8-track tape, 8-track cartridge is a musical recording format.
* "#8" is the stage name of Slipknot (band), Slipknot vocalist Corey Taylor.
* "Too Many Eights" is a song by Athens, Georgia's Supercluster (band), Supercluster.
* Eight Seconds, a Canadian musical group popular in the 1980s with their most notable song "Kiss You (When It's Dangerous)".
* "Eight Days a Week (song), Eight Days a Week" is a #1 single for the music group The Beatles.
* Figure 8 (album), ''Figure 8'' is the fifth studio album by singer-songwriter Elliott Smith, released in the year 2000, an album released by Julia Darling in 1999, and an album released by Outasight in 2011.
* Ming Hao from the k-pop group Seventeen (South Korean band)#Performance team, Seventeen goes by the name "The8".
* "8 (circle)" is the eighth song on the album ''22, A Million'' by the American band Bon Iver.
* "8" is the eighth song on the album ''When We All Fall Asleep, Where Do We Go?'' by Billie Eilish.
In film and television

* ''8 Guys'' is a 2003 short film written and directed by Dane Cook. * ''8 Man'' (or ''Eightman''): 1963 Japanese manga and anime superhero. * 8 Mile (film), ''8 Mile'' is a 2002 film directed by Curtis Hanson. * 8mm (film), ''8 mm'' is a 1999 film directed by Joel Schumacher. * ''8 Women'' (Original French title: ) is a 2001 film directed by François Ozon. * ''Eight Below'' is a 2006 film directed by Frank Marshall (film producer), Frank Marshall. * ''Eight Legged Freaks'' is a 2002 film directed by Ellory Elkayem. * ''Eight Men Out'' is a 1988 film directed by John Sayles. * ''Jennifer Eight'', also known as ''Jennifer 8'', is a 1992 film written and directed by Bruce Robinson. * ''Eight Is Enough'' is an American television comedy-drama series. * In ''Stargate SG-1'' and ''Stargate Atlantis'', dialing an 8-chevron address will open a wormhole to another galaxy. * ''The Hateful Eight'' is a 2015 American western mystery film written and directed by Quentin Tarantino. * ''Kate Plus 8'' is an American reality television show.In sports and other games

* Eight-ball pool (cue sports), pool is played with a cue ball and 15 numbered balls, the black ball numbered 8 being the middle and most important one, as the winner is the player or side that legally pockets it after first pocketing its numerical group of 7 object balls (for other meanings see ''Eight ball (disambiguation)''). * In chess, each side has eight pawns and the board is made of 64 squares arranged in an eight by eight lattice. The eight queens puzzle is a challenge to arrange eight queens on the board so that none can capture any of the others. * In the game of eights or Crazy Eights, each successive player must play a card either of the same suit or of the same rank as that played by the preceding player, or may play an eight and call for any suit. The object is to get rid of all one's cards first. * In association football, the number 8 has historically been the number of the Central Midfielder. * In Australian rules football, the top eight teams at the end of the Australian Football League regular season qualify for the AFL finals series, finals series (i.e. playoffs). * In baseball: ** The center fielder is designated as number 8 for scorekeeping purposes. ** The College World Series, the final phase of the NCAA Division I Baseball Championship, NCAA Division I tournament, features eight teams. * In rugby union, the only position without a proper name is the Number eight (rugby union), Number 8, a forward position. * In rugby league: ** Most competitions (though not the Super League, which uses static squad numbering) use a position-based player numbering system in which one of the two starting props wears the number 8. ** The Australia-based National Rugby League has its own 8-team finals series, similar but not identical in structure to that of the Australian Football League. * In Rowing (sport), rowing, an "eight" refers to a sweep-oar racing boat with a crew of eight rowers plus a coxswain. * In the 2008 Summer Olympics, 2008 Games of the XXIX Olympiad held in Beijing, the official opening was on 08/08/08 at 8:08:08 p.m. China Standard Time, CST. * In Rock Climbing, climbers frequently use the Figure-eight knot, Figure Eight knot to tie into their harnesses.In foods

* Nestlé sells a brand of chocolates filled with peppermint-flavoured cream called After Eight, referring to the time 8 p.m. * There are eight vegetables in V8 (beverage), V8 juice.In literature

* Eights may refer to octosyllable, octosyllabic, usually Choliamb, iambic, Meter (poetry), lines of verse. * The drott-kvaett, an Old Icelandic verse, consisted of a stanza of eight regular lines. * In Terry Pratchett's ''Discworld'' series, eight is a magical number and is considered taboo. Eight is not safe to be said by wizards on the Discworld (world), Discworld and is the number of Bel-Shamharoth. Also, there are eight days in a Disc week and eight colours in a Disc spectrum, the eighth one being octarine. * Lewis Carroll's poem ''The Hunting of the Snark'' has 8 "fits" (cantos), which is noted in the full name "The Hunting of the Snark – ''An Agony, in Eight Fits''." * Eight apparitions appear to Macbeth (character), Macbeth in Act 4 scene 1 of Shakespeare's ''Macbeth'' as representations of the eight descendants of Banquo.In slang

* An "eighth" is a common measurement of cannabis (drug), marijuana, meaning an eighth of an ounce. It is also a common unit of sale for psilocybin mushrooms. * Avril Lavigne's song "Sk8er Boi" uses this convention in the title. * "Section 8" is common U.S. slang for "crazy", based on the United States armed forces, U.S. military's Section 8 (military), Section 8 discharge for Mental disorder, mentally unfit personnel. * The Section 8 (housing), Housing Choice Voucher Program, operated by the United States Department of Housing and Urban Development, is commonly referred to as the Section 8 program, as this was the original section of the Act which instituted the program. * In Colombia and Venezuela, "volverse un ocho" (meaning to tie oneself in a figure 8) refers to getting in trouble or contradicting oneself. * In China, "8" is used in chat speak as a term for parting. This is due to the closeness in pronunciation of "8" (bā) and the English word "bye".See also

* The Magical Number Seven, Plus or Minus Two *List of highways numbered 8References

External links

The Octonions

John C. Baez {{DEFAULTSORT:8 (Number) Integers 8 (number)