9 (nine) is 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 ...

following and preceding .

Evolution of the Arabic digit

In the

beginning Beginning may refer to: * ''Beginning'' (album), by Pakho Chau * ''Beginning'' (play), a 2017 play by David Eldridge * ''Beginning'' (film), a Georgian-French drama film *"Beginning", a song by heavy metal band Kotipelto *"Beginning", a 2018 trac ...

, various Indians wrote a digit 9 similar in shape to the modern closing

question mark The question mark (also known as interrogation point, query, or eroteme in journalism) is a punctuation mark that indicates an interrogative clause or phrase in many languages. History In the fifth century, Syriac Bible manuscripts used ...

without the bottom dot. The Kshatrapa, Andhra and Gupta started curving the bottom vertical line coming up with a -look-alike. The Nagari continued the bottom stroke to make a circle and enclose the 3-look-alike, in much the same way that the sign @ encircles a lowercase ''a''. As time went on, the enclosing circle became bigger and its line continued beyond the circle downwards, as the 3-look-alike became smaller. Soon, all that was left of the 3-look-alike was a squiggle. The Arabs simply connected that squiggle to the downward stroke at the middle and subsequent European change was purely cosmetic. While the shape of the glyph for the digit 9 has an ascender 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 thousands o ...

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 usually has a

descender In typography and handwriting, a descender is the portion of a letter that extends below the baseline of a font. For example, in the letter ''y'', the descender is the "tail", or that portion of the diagonal line which lies below the ''v' ...

, as, for example, in TextFigs196

. The modern digit resembles an inverted ''6''. To disambiguate the two on objects and documents that can be inverted, they are often underlined. Another distinction from the 6 is that it is sometimes handwritten with two strokes and a straight stem, resembling a raised lower-case letter q. 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, bas ...

, the number 9 can be constructed in two ways, either with a hook at the end of its stem or without one. Most LCD calculators use the former, but some VFD models use the latter.

Mathematics

Nine is the fourth

composite 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 In mathematics, a divisor of an integer n, also called a factor ...

, and the first composite number that is odd. 9 is the highest single-digit number in the decimal system. It is the third

square number In mathematics, a square number or perfect square is an integer that is the square of an integer; in other words, it is the product of some integer with itself. For example, 9 is a square number, since it equals and can be written as . The u ...

(3²), and the second non-unitary square

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 ...

of the form ''p''² and first that is odd, with all subsequent squares of this form odd as well. 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 ...

, 9 is the only positive

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 more than another positive perfect power, since the

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 a ...

of 3 is one more than the

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 ...

of 2. A number that is 4 or 5

modulo In computing, the modulo operation returns the remainder or signed remainder of a division, after one number is divided by another (called the '' modulus'' of the operation). Given two positive numbers and , modulo (often abbreviated as ) is ...

9 cannot be represented as the sum of three cubes. MotzkinChords4

9 is a

Motzkin number In mathematics, the th Motzkin number is the number of different ways of drawing non-intersecting chords between points on a circle (not necessarily touching every point by a chord). The Motzkin numbers are named after Theodore Motzkin and have d ...

, for the number of ways of drawing non-intersecting

chords Chord may refer to: * Chord (music), an aggregate of musical pitches sounded simultaneously ** Guitar chord a chord played on a guitar, which has a particular tuning * Chord (geometry), a line segment joining two points on a curve * Chord ( ...

between four points on a

circle A circle is a shape consisting of all points in a plane that are at a given distance from a given point, the centre. Equivalently, it is the curve traced out by a point that moves in a plane so that its distance from a given point is cons ...

. Since , 9 is an exponential factorial. Six recurring nines appear in the decimal places 762 through 767 of . (See

six nines in pi A sequence of six consecutive nines occurs in the decimal representation of the number pi (), starting at the 762nd decimal place.. It has become famous because of the mathematical coincidence and because of the idea that one could memorize the d ...

). The first non-trivial

magic square In recreational mathematics, a square array of numbers, usually positive integers, is called a magic square if the sums of the numbers in each row, each column, and both main diagonals are the same. The 'order' of the magic square is the number ...

is a

3

3

magic square made of nine cells, with a

magic constant The magic constant or magic sum of a magic square is the sum of numbers in any row, column, or diagonal of the magic square. For example, the magic square shown below has a magic constant of 15. For a normal magic square of order ''n'' – that is ...

of 15; there are no

2

2

magic squares with four cells. Meanwhile, a

9

9

magic square has a magic constant of

369 __NOTOC__ Year 369 ( CCCLXIX) was a common year starting on Thursday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Galates and Victor (or, less frequently, year 1122 ' ...

. 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 ...

with nine sides is called a

nonagon In geometry, a nonagon () or enneagon () is a nine-sided polygon or 9-gon. The name ''nonagon'' is a prefix hybrid formation, from Latin (''nonus'', "ninth" + ''gonon''), used equivalently, attested already in the 16th century in French ''nonogo ...

. Also an ''enneagon'', it is able to fill a plane-vertex alongside an

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 oth ...

and an regular

octadecagon In geometry, an octadecagon (or octakaidecagon) or 18-gon is an eighteen-sided polygon. Regular octadecagon A '' regular octadecagon'' has a Schläfli symbol and can be constructed as a quasiregular truncated enneagon, t, which alternates tw ...

, or 18-sided

. There are nine distinct

uniform coloring In geometry, a uniform coloring is a property of a uniform figure (uniform tiling or uniform polyhedron) that is colored to be vertex-transitive. Different symmetries can be expressed on the same geometric figure with the faces following differ ...

s of the

triangular tiling In geometry, the triangular tiling or triangular tessellation is one of the three regular tilings of the Euclidean plane, and is the only such tiling where the constituent shapes are not parallelogons. Because the internal angle of the equilater ...

and the

square tiling In geometry, the square tiling, square tessellation or square grid is a regular tiling of the Euclidean plane. It has Schläfli symbol of meaning it has 4 squares around every vertex. Conway called it a quadrille. The internal angle of th ...

, which are the two simplest

regular tilings This article lists the regular polytopes and regular polytope compounds in Euclidean, spherical and hyperbolic spaces. The Schläfli symbol describes every regular tessellation of an ''n''-sphere, Euclidean and hyperbolic spaces. A Schläfli sy ...

; the

hexagonal tiling In geometry, the hexagonal tiling or hexagonal tessellation is a regular tiling of the Euclidean plane, in which exactly three hexagons meet at each vertex. It has Schläfli symbol of or (as a truncated triangular tiling). English mathemati ...

, on the other hand, has three distinct uniform colorings. There are nine

edge-transitive In geometry, a polytope (for example, a polygon or a polyhedron) or a tiling is isotoxal () or edge-transitive if its symmetries act transitively on its edges. Informally, this means that there is only one type of edge to the object: given t ...

convex polyhedra in

three dimensions Three-dimensional space (also: 3D space, 3-space or, rarely, tri-dimensional space) is a geometric setting in which three values (called '' parameters'') are required to determine the position of an element (i.e., point). This is the inform ...

: *the five regular Platonic solids: the

tetrahedron 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 ...

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 ...

dodecahedron In geometry, a dodecahedron (Greek , from ''dōdeka'' "twelve" + ''hédra'' "base", "seat" or "face") or duodecahedron is any polyhedron with twelve flat faces. The most familiar dodecahedron is the regular dodecahedron with regular pentagon ...

and

icosahedron In geometry, an icosahedron ( or ) is a polyhedron with 20 faces. The name comes and . The plural can be either "icosahedra" () or "icosahedrons". There are infinitely many non- similar shapes of icosahedra, some of them being more symmetrica ...

; *the two quasiregular

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 compose ...

s: 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 ...

and the

icosidodecahedron In geometry, an icosidodecahedron is a polyhedron with twenty (''icosi'') triangular faces and twelve (''dodeca'') pentagonal faces. An icosidodecahedron has 30 identical vertices, with two triangles and two pentagons meeting at each, and 60 i ...

; and *two

Catalan solid In mathematics, a Catalan solid, or Archimedean dual, is a dual polyhedron to an Archimedean solid. There are 13 Catalan solids. They are named for the Belgian mathematician Eugène Catalan, who first described them in 1865. The Catalan so ...

s: the

rhombic dodecahedron In geometry, the rhombic dodecahedron is a convex polyhedron with 12 congruent rhombic faces. It has 24 edges, and 14 vertices of 2 types. It is a Catalan solid, and the dual polyhedron of the cuboctahedron. Properties The rhombic dodecahed ...

and the

rhombic triacontahedron In geometry, the rhombic triacontahedron, sometimes simply called the triacontahedron as it is the most common thirty-faced polyhedron, is a convex polyhedron with 30 rhombic faces. It has 60 edges and 32 vertices of two types. It is a Ca ...

, which are

duals ''Duals'' is a compilation album by the Irish rock band U2. It was released in April 2011 to u2.com subscribers. Track listing :* "Where the Streets Have No Name" and "Amazing Grace" are studio mix of U2's performance at the Rose Bowl, P ...

to the only two quasiregular polyhedra. In

four-dimensional space A four-dimensional space (4D) is a mathematical extension of the concept of three-dimensional or 3D space. Three-dimensional space is the simplest possible abstraction of the observation that one only needs three numbers, called ''dimensions'', ...

, there are nine paracompact hyperbolic honeycomb

Coxeter group In mathematics, a Coxeter group, named after H. S. M. Coxeter, is an abstract group that admits a formal description in terms of reflections (or kaleidoscopic mirrors). Indeed, the finite Coxeter groups are precisely the finite Euclidean refle ...

s, as well as nine regular compact hyperbolic honeycombs from regular

convex Convex or convexity may refer to: Science and technology * Convex lens, in optics Mathematics * Convex set, containing the whole line segment that joins points ** Convex polygon, a polygon which encloses a convex set of points ** Convex polytop ...

and

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

'' polychora''. There are also nine uniform demitesseractic (

\mathrm D_

) Euclidean honeycombs in the fourth dimension. There are only three types of

Coxeter groups In mathematics, a Coxeter group, named after H. S. M. Coxeter, is an abstract group that admits a formal description in terms of reflections (or kaleidoscopic mirrors). Indeed, the finite Coxeter groups are precisely the finite Euclidean refle ...

of uniform figures in dimensions

nine 9 is a number, numeral, and glyph. 9 or nine may also refer to: Dates * AD 9, the ninth year of the AD era * 9 BC, the ninth year before the AD era * 9, numerical symbol for the month of September Places * Nine, Portugal, a parish in the ...

and thereafter, aside from the many families of

prisms Prism usually refers to: * Prism (optics), a transparent optical component with flat surfaces that refract light * Prism (geometry), a kind of polyhedron Prism may also refer to: Science and mathematics * Prism (geology), a type of sedimentar ...

and

proprism In geometry of 4 dimensions or higher, a proprism is a polytope resulting from the Cartesian product of two or more polytopes, each of two dimensions or higher. The term was coined by John Horton Conway for ''product prism''. The dimension of the ...

s: the

\mathrm A_

simplex In geometry, a simplex (plural: simplexes or simplices) is a generalization of the notion of a triangle or tetrahedron to arbitrary dimensions. The simplex is so-named because it represents the simplest possible polytope in any given dimension. ...

groups, the

\mathrm B_

hypercube In geometry, a hypercube is an ''n''-dimensional analogue of a square () and a cube (). It is a closed, compact, convex figure whose 1-skeleton consists of groups of opposite parallel line segments aligned in each of the space's dimensions, p ...

groups, and the

\mathrm D_

demihypercube groups. The ninth dimension is also the final dimension that contains Coxeter-Dynkin diagrams as uniform solutions in

hyperbolic space In mathematics, hyperbolic space of dimension n is the unique simply connected, n-dimensional Riemannian manifold of constant sectional curvature equal to -1. It is homogeneous, and satisfies the stronger property of being a symmetric space. The ...

. Inclusive of compact hyperbolic solutions, there are a total of 238 compact and paracompact Coxeter-Dynkin diagrams between dimensions two and nine, or equivalently between ranks three and ten. The most important of the last

_9

paracompact groups is the group

_9

with

1023 Year 1023 ( MXXIII) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. Events By place Europe * The Judge-Governor of Seville in Al-Andalus (modern Spain) takes advantage of the disinte ...

total honeycombs, the simplest of which is 6₂₁ whose

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 of a polyhedron. Mark a point somewhere along each connected edge. Draw line ...

is the 5₂₁ honeycomb: the vertex arrangement of the densest-possible packing of spheres in 8 dimensions which forms the

\mathbb E_

lattice. The 6₂₁ honeycomb is made of

9-simplex In geometry, a 9- simplex is a self-dual regular 9-polytope. It has 10 vertices, 45 edges, 120 triangle faces, 210 tetrahedral cells, 252 5-cell 4-faces, 210 5-simplex 5-faces, 120 6-simplex 6-faces, 45 7-simplex 7-faces, and 10 8-simplex 8-fa ...

es and

9-orthoplex In geometry, a 9-orthoplex or 9-cross polytope, is a regular 9-polytope with 18 vertices, 144 edges, 672 triangle faces, 2016 tetrahedron cells, 4032 5-cells ''4-faces'', 5376 5-simplex ''5-faces'', 4608 6-simplex ''6-faces'', 2304 7-simplex ''7 ...

es, with 1023 total polytope elements making up each 9-simplex. It is the final honeycomb figure with infinite facets and vertex figures in the k₂₁ family of

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 Polyt ...

s, first defined by

Thorold Gosset John Herbert de Paz Thorold Gosset (16 October 1869 – December 1962) was an English lawyer and an amateur mathematician. In mathematics, he is noted for discovering and classifying the semiregular polytopes in dimensions four and higher, ...

in 1900. There are nine

Heegner number In number theory, a Heegner number (as termed by Conway and Guy) is a square-free positive integer ''d'' such that the imaginary quadratic field \Q\left sqrt\right/math> has class number 1. Equivalently, its ring of integers has unique factori ...

s, or square-free positive integers

n

that yield an imaginary

quadratic field In algebraic number theory, a quadratic field is an algebraic number field of degree two over \mathbf, the rational numbers. Every such quadratic field is some \mathbf(\sqrt) where d is a (uniquely defined) square-free integer different from 0 a ...

\Q\left sqrt\right /math> whose

ring of integers In mathematics, the ring of integers of an algebraic number field K is the ring of all algebraic integers contained in K. An algebraic integer is a root of a monic polynomial with integer coefficients: x^n+c_x^+\cdots+c_0. This ring is often deno ...

has a unique factorization, or class number of 1.

In decimal

A positive number is divisible by nine

if and only if In logic and related fields such as mathematics and philosophy, "if and only if" (shortened as "iff") is a biconditional logical connective between statements, where either both statements are true or both are false. The connective is bic ...

its

digital root The digital root (also repeated digital sum) of a natural number in a given radix is the (single digit) value obtained by an iterative process of summing digits, on each iteration using the result from the previous iteration to compute a digit su ...

is nine. That is, if any

is multiplied by 9, and the digits of the answer are repeatedly added until it is just one digit, the sum will be nine: *2 × 9 = 18 (1 + 8 = 9) *3 × 9 = 27 (2 + 7 = 9) *9 × 9 = 81 (8 + 1 = 9) *121 × 9 = 1089 (1 + 0 + 8 + 9 = 18; 1 + 8 = 9) *234 × 9 = 2106 (2 + 1 + 0 + 6 = 9) *578329 × 9 = 5204961 (5 + 2 + 0 + 4 + 9 + 6 + 1 = 27; 2 + 7 = 9) *482729235601 × 9 = 4344563120409 (4 + 3 + 4 + 4 + 5 + 6 + 3 + 1 + 2 + 0 + 4 + 0 + 9 = 45; 4 + 5 = 9) There are other interesting patterns involving multiples of nine: *12345679 × 9 = 111111111 *12345679 × 18 = 222222222 *12345679 × 81 = 999999999 This works for all the multiples of 9. is the only other such that a number is divisible by ''n'' if and only if its digital root is divisible by ''n''. In base-''N'', the

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 of have this property. Another consequence of 9 being , is that it is also a

Kaprekar number In mathematics, a natural number in a given number base is a p-Kaprekar number if the representation of its square in that base can be split into two parts, where the second part has p digits, that add up to the original number. The numbers are n ...

. The difference between a base-10 positive integer and the sum of its digits is a whole multiple of nine. Examples: *The sum of the digits of 41 is 5, and 41 − 5 = 36. The digital root of 36 is 3 + 6 = 9, which, as explained above, demonstrates that it is divisible by nine. *The sum of the digits of 35967930 is 3 + 5 + 9 + 6 + 7 + 9 + 3 + 0 = 42, and 35967930 − 42 = 35967888. The digital root of 35967888 is 3 + 5 + 9 + 6 + 7 + 8 + 8 + 8 = 54, 5 + 4 = 9. If dividing a number by the amount of 9s corresponding to its number of digits, the number is turned into a

repeating decimal A repeating decimal or recurring decimal is decimal representation of a number whose digits are periodic (repeating its values at regular intervals) and the infinitely repeated portion is not zero. It can be shown that a number is rational i ...

. (e.g. )

Casting out nines Casting out nines is any of three arithmetical procedures: *Adding the decimal digits of a positive whole number, while optionally ignoring any 9s or digits which sum to a multiple of 9. The result of this procedure is a number which is smaller th ...

is a quick way of testing the calculations of sums, differences, products, and quotients of integers known as long ago as the 12th century.

List of basic calculations

Alphabets and codes

*In the

NATO phonetic alphabet The (International) Radiotelephony Spelling Alphabet, commonly known as the NATO phonetic alphabet, is the most widely used set of clear code words for communicating the letters of the Roman alphabet, technically a ''radiotelephonic spellin ...

, the digit 9 is called "Niner". *Five-digit

produce Produce is a generalized term for many farm-produced crops, including fruits and vegetables ( grains, oats, etc. are also sometimes considered ''produce''). More specifically, the term ''produce'' often implies that the products are fres ...

PLU codes that begin with 9 are

organic Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ Chemistry * Organic matter, matter that has come from a once-living organism, is capable of decay or is the product ...

Culture and mythology

Indian culture

Nine is a number that appears often in

Indian culture Indian culture is the heritage of social norms, ethical values, traditional customs, belief systems, political systems, artifacts and technologies that originated in or are associated with the ethno-linguistically diverse India. The term ...

and mythology. Some instances are enumerated below. *Nine

influencers An Internet celebrity (also known as a social media influencer, social media personality, internet personality, or simply influencer) is a celebrity who has acquired or developed their fame and notability through the Internet. The rise of social m ...

are attested in

Indian astrology Jyotisha or Jyotishya (from Sanskrit ', from ' “light, heavenly body" and ''ish'' - from Isvara or God) is the traditional Hindu system of astrology, also known as Hindu astrology, Indian astrology and more recently Vedic astrology. It is one ...

. *In the

Vaisheshika Vaisheshika or Vaiśeṣika ( sa, वैशेषिक) is one of the six schools of Indian philosophy (Vedic systems) from ancient India. In its early stages, the Vaiśeṣika was an independent philosophy with its own metaphysics, epistemolog ...

branch of

Hindu philosophy Hindu philosophy encompasses the philosophies, world views and teachings of Hinduism that emerged in Ancient India which include six systems ('' shad-darśana'') – Samkhya, Yoga, Nyaya, Vaisheshika, Mimamsa and Vedanta.Andrew Nicholson ( ...

, there are nine universal substances or elements:

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's sur ...

Water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ...

Air The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing f ...

Fire Fire is the rapid oxidation of a material (the fuel) in the exothermic chemical process of combustion, releasing heat, light, and various reaction products. At a certain point in the combustion reaction, called the ignition point, flames ...

Ether In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again ...

Time Time is the continued sequence of existence and event (philosophy), events that occurs in an apparently irreversible process, irreversible succession from the past, through the present, into the future. It is a component quantity of various me ...

Space Space is the boundless three-dimensional extent in which objects and events have relative position and direction. In classical physics, physical space is often conceived in three linear dimensions, although modern physicists usually consi ...

Soul In many religious and philosophical traditions, there is a belief that a soul is "the immaterial aspect or essence of a human being". Etymology The Modern English noun '' soul'' is derived from Old English ''sāwol, sāwel''. The earliest att ...

, and

Mind The mind is the set of faculties responsible for all mental phenomena. Often the term is also identified with the phenomena themselves. These faculties include thought, imagination, memory, will, and sensation. They are responsible for various m ...

. *

Navaratri Navaratri is an annual Hindu festival observed in the honour of the goddess Durga. It spans over nine nights (and ten days), first in the month of Chaitra (March/April of the Gregorian calendar), and again in the month of Sharada. It is o ...

is a nine-day festival dedicated to the

forms of

Durga Durga ( sa, दुर्गा, ) is a major Hindu goddess, worshipped as a principal aspect of the mother goddess Mahadevi. She is associated with protection, strength, motherhood, destruction, and wars. Durga's legend centres around c ...

. * Navaratna, meaning "nine jewels" may also refer to

Navaratnas Navaratnas (Sanskrit dvigu ''nava-ratna'', ) () or Nauratan was a term applied to a group of nine extraordinary people in an emperor's court in India. The well-known Nauratnas include the ones in the courts of the Hindu emperor Vikramaditya, the ...

– accomplished courtiers, Navratan – a kind of dish, or a form of

architecture Architecture is the art and technique of designing and building, as distinguished from the skills associated with construction. It is both the process and the product of sketching, conceiving, planning, designing, and constructing buildings ...

. *In

Indian aesthetics Indian art evolved with an emphasis on inducing special spiritual or philosophical states in the audience, or with representing them symbolically. Rasas in the performing arts The theory of rasas still forms the aesthetic underpinning of a ...

, there are nine kinds of Rasa.

Chinese culture

*Nine (

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 fo ...

jiǔ) is considered a good number in Chinese culture because it sounds the same as the word "long-lasting" (

jiǔ). *Nine is strongly associated with the

Chinese dragon The Chinese dragon, also known as ''loong'', ''long'' or ''lung'', is a legendary creature in Chinese mythology, Chinese folklore, and Chinese culture at large. Chinese dragons have many Outline of life forms, animal-like forms such as Bixi (my ...

, a symbol of magic and power. There are nine forms of the dragon, it is described in terms of nine attributes, and it has nine children. It has 117 scales – 81 yang (masculine, heavenly) and 36

yin Yin may refer to: *the dark force in the yin and yang from traditional Chinese philosophy and medicine *Yīn (surname) (), a Chinese surname *Yǐn (surname) (), a Chinese surname *Shang dynasty, also known as the Yin dynasty **Yinxu or Yin, the S ...

(feminine, earthly). All three numbers are multiples of 9 (, , ) as well as having the same

of 9. *The dragon often symbolizes the

Emperor An emperor (from la, imperator, via fro, empereor) is a monarch, and usually the sovereign ruler of an empire or another type of imperial realm. Empress, the female equivalent, may indicate an emperor's wife ( empress consort), mother ( ...

, and the number nine can be found in many ornaments in the

Forbidden City The Forbidden City () is a palace complex in Dongcheng District, Beijing, China, at the center of the Imperial City of Beijing. It is surrounded by numerous opulent imperial gardens and temples including the Zhongshan Park, the sacrifi ...

. *The circular altar platform (''Earthly Mount'') of the

Temple of Heaven The Temple of Heaven () is a complex of imperial religious buildings situated in the southeastern part of central Beijing. The complex was visited by the Emperors of the Ming and Qing dynasties for annual ceremonies of prayer to Heaven for a ...

has one circular marble plate in the center, surrounded by a ring of nine plates, then by a ring of 18 plates, and so on, for a total of nine rings, with the outermost having *The name of the area called ''

Kowloon Kowloon () is an urban area in Hong Kong comprising the Kowloon Peninsula and New Kowloon. With a population of 2,019,533 and a population density of in 2006, it is the most populous area in Hong Kong, compared with Hong Kong Island and ...

'' in Hong Kong literally means: ''nine

dragons A dragon is a reptilian legendary creature that appears in the folklore of many cultures worldwide. Beliefs about dragons vary considerably through regions, but dragons in western cultures since the High Middle Ages have often been depicted as ...

''. *The nine-dotted line () delimits certain island claims by China in the South China Sea. *The

nine-rank system The nine-rank system, also known as the nine-grade controller system, was used to categorize and classify government officials in Imperial China. Created in the state of Cao Wei during the Three Kingdoms, it was used until the Song dynasty, and ...

was a civil service nomination system used during certain Chinese dynasties. *9 Points of the

Heart The heart is a muscular Organ (biology), organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as ca ...

( Heal) / Heart Master (

Immortality Immortality is the concept of eternal life. Some modern species may possess biological immortality. Some scientists, futurists, and philosophers have theorized about the immortality of the human body, with some suggesting that human immorta ...

) Channels in

Traditional Chinese Medicine Traditional Chinese medicine (TCM) is an alternative medical practice drawn from traditional medicine in China. It has been described as "fraught with pseudoscience", with the majority of its treatments having no logical mechanism of acti ...

Ancient Egypt

*The nine bows is a term used in Ancient Egypt to represent the traditional enemies of Egypt. *The

Ennead The Ennead or Great Ennead was a group of nine Egyptian pantheon, deities in Egyptian mythology worshipped at Heliopolis (Ancient Egypt), Heliopolis: the sun god Atum; his children Shu (Egyptian deity), Shu and Tefnut; their children Geb and Nu ...

is a group of nine Egyptian deities, who, in some versions of the

Osiris myth The Osiris myth is the most elaborate and influential story in ancient Egyptian mythology. It concerns the murder of the god Osiris, a primeval king of Egypt, and its consequences. Osiris's murderer, his brother Set, usurps his throne. Meanwhil ...

, judged whether

Horus Horus or Heru, Hor, Har in Ancient Egyptian, is one of the most significant ancient Egyptian deities who served many functions, most notably as god of kingship and the sky. He was worshipped from at least the late prehistoric Egypt until the ...

Set Set, The Set, SET or SETS may refer to: Science, technology, and mathematics Mathematics *Set (mathematics), a collection of elements *Category of sets, the category whose objects and morphisms are sets and total functions, respectively Electro ...

should inherit Egypt.

European culture

*The

Nine Worthies The Nine Worthies are nine historical, scriptural, and legendary men of distinction who personify the ideals of chivalry established in the Middle Ages, whose lives were deemed a valuable study for aspirants to chivalric status. All were commonly ...

are nine historical, or semi-legendary figures who, in the Middle Ages, were believed to personify the ideals of chivalry. *In

Norse mythology Norse, Nordic, or Scandinavian mythology is the body of myths belonging to the North Germanic peoples, stemming from Old Norse religion and continuing after the Christianization of Scandinavia, and into the Nordic folklore of the modern per ...

, the universe is divided into

nine worlds Norse cosmology is the study of the cosmos (cosmology) as perceived by the ancient North Germanic peoples. The topic encompasses concepts from Norse mythology, such as notions of time and space, cosmogony, personifications, anthropogeny, and escha ...

which are all connected by the

world tree The world tree is a motif present in several religions and mythologies, particularly Indo-European religions, Siberian religions, and Native American religions. The world tree is represented as a colossal tree which supports the heavens, thereb ...

Yggdrasil *In

as well, the number nine is associated with

Odin Odin (; from non, Óðinn, ) is a widely revered god in Germanic paganism. Norse mythology, the source of most surviving information about him, associates him with wisdom, healing, death, royalty, the gallows, knowledge, war, battle, victory, ...

, as that is how many days he hung from the

Yggdrasil before attaining knowledge of the

runes Runes are the letters in a set of related alphabets known as runic alphabets native to the Germanic peoples. Runes were used to write various Germanic languages (with some exceptions) before they adopted the Latin alphabet, and for specialised ...

Greek mythology

*The nine

Muse In ancient Greek religion and mythology, the Muses ( grc, Μοῦσαι, Moûsai, el, Μούσες, Múses) are the inspirational goddesses of literature, science, and the arts. They were considered the source of the knowledge embodied in ...

s in Greek mythology are

Calliope In Greek mythology, Calliope ( ; grc, Καλλιόπη, Kalliópē, beautiful-voiced) is the Muse who presides over eloquence and epic poetry; so called from the ecstatic harmony of her voice. Hesiod and Ovid called her the "Chief of all Muse ...

(epic poetry),

Clio In Greek mythology, Clio ( , ; el, Κλειώ), also spelled Kleio, is the muse of history, or in a few mythological accounts, the muse of lyre playing. Etymology Clio's name is etymologically derived from the Greek root κλέω/κλε ...

(history),

Erato In Greek mythology, Erato (; grc, Ἐρατώ) is one of the Greek Muses, which were inspirational goddesses of literature, science, and the arts. The name would mean "desired" or "lovely", if derived from the same root as Eros, as Apollonius ...

(erotic poetry),

Euterpe Euterpe (; el, Εὐτέρπη, lit=rejoicing well' or 'delight , from grc, εὖ, eû, well + el, τέρπειν, térpein, to please) was one of the Muses in Greek mythology, presiding over music. In late Classical times, she was named muse ...

(lyric poetry),

Melpomene In Greek mythology, Melpomene (; grc, Μελπομένη, Melpoménē, to sing' or 'the one that is melodious), initially the muse of chorus, eventually became the muse of tragedy, and is now best known in that association. Etymology Mel ...

(tragedy),

Polyhymnia Polyhymnia (; el, Πολυύμνια, lit=the one of many hymns), alternatively Polymnia (Πολύμνια), was, in Greek mythology, the Muse of sacred poetry, sacred hymn, dance and eloquence, as well as agriculture and pantomime. Etymology ...

(song),

Terpsichore In Greek mythology, Terpsichore (; grc-gre, Τερψιχόρη, "delight in dancing") is one of the nine Muses and goddess of dance and chorus. She lends her name to the word "terpsichorean" which means "of or relating to dance". Appearance ...

(dance), Thalia (comedy), and

Urania Urania ( ; grc, , Ouranía; modern Greek shortened name ''Ránia''; meaning "heavenly" or "of heaven") was, in Greek mythology, the muse of astronomy, and in later times, of Christian poetry. Urania is the goddess of astronomy and stars, ...

(astronomy). *It takes nine days (for an anvil) to fall from heaven to earth, and nine more to fall from earth to

Tartarus In Greek mythology, Tartarus (; grc, , }) is the deep abyss that is used as a dungeon of torment and suffering for the wicked and as the prison for the Titans. Tartarus is the place where, according to Plato's ''Gorgias'' (), souls are judg ...

. *

Leto In ancient Greek mythology and religion, Leto (; grc-gre, Λητώ , ''Lētṓ'', or , ''Lātṓ'' in Doric Greek) is a goddess and the mother of Apollo, the god of music, and Artemis, the goddess of the hunt.Hesiod, ''Theogony'404–409/ref> ...

labored for nine days and nine nights for

Apollo Apollo, grc, Ἀπόλλωνος, Apóllōnos, label=genitive , ; , grc-dor, Ἀπέλλων, Apéllōn, ; grc, Ἀπείλων, Apeílōn, label=Arcadocypriot Greek, ; grc-aeo, Ἄπλουν, Áploun, la, Apollō, la, Apollinis, label= ...

, according to the Homeric Hymn to Delian Apollo.

Mesoamerican mythology

* The

Lords of the Night In Mesoamerican mythology the Lords of the Night ( nci, Yoalteuctin) are a set of nine gods who each ruled over every ninth night forming a calendrical cycle. Each lord was associated with a particular fortune, bad or good, that was an omen for ...

, is a group of nine deities who each ruled over every ninth night forming a calendrical cycle

Aztec mythology

* Mictlan the underworld in Aztec mythology, consists of nine levels.

Mayan mythology

* The Mayan underworld

Xibalba (), roughly translated as "place of fright", is the name of the underworld (or quc, Mitnal) in Maya mythology, ruled by the Maya death gods and their helpers. In 16th-century Verapaz, the entrance to Xibalba was traditionally held to be a ...

consists of nine levels. * El Castillo the Mayan step-pyramid in Chichén Itzá, consists of nine steps. It is said that this was done to represent the nine levels of

Anthropology

Idioms

*"to go the whole nine yards-" *"A

cat-o'-nine-tails The cat o' nine tails, commonly shortened to the cat, is a type of multi-tailed whip or flail that originated as an implement for severe physical punishment, notably in the Royal Navy and British Army, and as a judicial punishment in Britain ...

suggests perfect punishment and atonement." –

Robert Ripley LeRoy Robert Ripley (February 22, 1890 – May 27, 1949) was an American cartoonist, entrepreneur, and amateur anthropologist, who is known for creating the ''Ripley's Believe It or Not!'' newspaper panel series, television show, and radio show, ...

. *"A cat has nine lives" *"to be on cloud nine" *"A stitch in time saves nine" *"found true 9 out of 10 times" *"possession is nine tenths of the law" *The word "K-9" pronounces the same as ''canine'' and is used in many US police departments to denote the police dog unit. Despite not sounding like the translation of the word ''canine'' in other languages, many police and military units around the world use the same designation. *Someone dressed "to the nines" is dressed up as much as they can be. *In North American

urban culture Urban culture is the culture of towns and cities. The defining theme is the presence of a great number of very different people in a very limited space - most of them are strangers to each other but still try to be polite to each other more times ...

, "nine" is a slang word for a 9mm

pistol A pistol is a handgun, more specifically one with the chamber integral to its gun barrel, though in common usage the two terms are often used interchangeably. The English word was introduced in , when early handguns were produced in Europe, a ...

homicide Homicide occurs when a person kills another person. A homicide requires only a volitional act or omission that causes the death of another, and thus a homicide may result from accidental, reckless, or negligent acts even if there is no inten ...

, the latter from the Illinois Criminal Code for homicide.

Society

*'' The 9 on Yahoo!'', hosted by

Maria Sansone Maria Grace Sansone (born February 26, 1981) is an American television personality. Sansone is the former co-anchor of '' Good Day LA'' on KTTV Fox 11 in Los Angeles until January 2017 and is a former field reporter for WNBC 4 New York, appeari ...

, was a daily video compilation show, or vlog, on Yahoo! featuring the nine top "web finds" of the day. *Nine justices sit on the

United States Supreme Court The Supreme Court of the United States (SCOTUS) is the highest court in the federal judiciary of the United States. It has ultimate appellate jurisdiction over all U.S. federal court cases, and over state court cases that involve a point o ...

. *Nine justices sit on the

Supreme Court of Canada The Supreme Court of Canada (SCC; french: Cour suprême du Canada, CSC) is the Supreme court, highest court in the Court system of Canada, judicial system of Canada. It comprises List of Justices of the Supreme Court of Canada, nine justices, wh ...

Technique

Stanine Stanine (STAndard NINE) is a method of scaling test scores on a nine-point standard scale with a mean of five and a standard deviation of two. Some web sources attribute stanines to the U.S. Army Air Forces during World War II. Psychometric lege ...

s, a method of scaling test scores, range from 1 to 9. *There are 9

square feet The square foot (plural square feet; abbreviated sq. ft, sf, or ft2; also denoted by '2) is an imperial unit and U.S. customary unit (non- SI, non-metric) of area, used mainly in the United States and partially in Canada, the United Kingdom, Bang ...

in a

square yard The square yard ( Northern India: gaj, Pakistan: gaz) is an imperial unit and U.S. customary unit of area. It is in widespread use in most of the English-speaking world, particularly the United States, United Kingdom, Canada, Pakistan and Indi ...

Pseudoscience

* 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 ...

the number 9 symbolizes the end of one cycle and the beginning of another.

Literature

*There are nine circles of Hell in Dante's ''

Divine Comedy The ''Divine Comedy'' ( it, Divina Commedia ) is an Italian narrative poem by Dante Alighieri, begun 1308 and completed in around 1321, shortly before the author's death. It is widely considered the pre-eminent work in Italian literature a ...

''. *The Nine Bright Shiners, characters in Garth Nix's Old Kingdom trilogy. ''The Nine Bright Shiners'' was a 1930s book of poems by Anne Ridler and a 1988 fiction book by Anthea Fraser; the name derives from "a very curious old semi-pagan, semi-Christian" song. *''

The Nine Tailors ''The Nine Tailors'' is a 1934 mystery novel by the British writer Dorothy L. Sayers, her ninth featuring Lord Peter Wimsey. The story is set in the Lincolnshire Fens, and revolves around a group of bell-ringers at the local parish church. The b ...

'' is a 1934 mystery novel by British writer Dorothy L. Sayers, her ninth featuring sleuth Lord Peter Wimsey. *Nine Unknown Men are, in occult legend, the custodians of the sciences of the world since ancient times. *In J. R. R. Tolkien's Middle-earth, there are nine rings of power given to men, and consequently, nine Nazgûl, ringwraiths. Additionally, The Fellowship of the Ring#Members of the Fellowship of the Ring, The Fellowship of the Ring consists of nine companions. *In ''Lorien Legacies'' there are nine Garde sent to Earth. *Number Nine is a character in ''Lorien Legacies''. *In the series ''A Song of Ice and Fire'', there are nine regions of Westeros (the Crownlands, the North, the Riverlands, the Westerlands, the Reach, the Stormlands, the Vale of Arryn, the Iron Islands and Dorne). Additionally, there is a group of nine city-states in western Essos known collectively as the Free Cities (Braavos, Lorath, Lys, Myr, Norvos, Pentos, Qohor, Tyrosh and Volantis). *In ''The Wheel of Time'' series, Daughter of the Nine Moons is the title given to the heir to the throne of Seanchan, and the Court of the Nine Moons serves as the throne room of the Seanchan rulers themselves. Additionally, the nation of Illian is partially governed by a body known as the Council of Nine, and the flag of Illian displays nine golden bees on it. Furthermore, in the Age of Legends, the Nine Rods of Dominion were nine regional governors who administered individual areas of the world under the ruling world government.

Organizations

*Divine Nine – The National Pan-Hellenic Council (NPHC) is a collaborative organization of nine historically African American, international Greek-lettered fraternities and sororities.

Places and thoroughfares

*List of highways numbered 9 *Ninth Avenue (Manhattan), Ninth Avenue is a major avenue in Manhattan. *Provinces of South Africa, South Africa has 9 provinces * Negeri Sembilan, a Malaysian States in Malaysia, state located in Peninsular Malaysia, is named as such as it was historically a confederation of nine ( ms, sembilan) settlements (''nagari (settlement), nagari'') of the Minangkabau people, Minangkabau migrated from West Sumatra.

Religion and philosophy

*Nine, as the highest single-digit number (in decimal, base ten), symbolizes completeness in the Baháʼí Faith. In addition, the word Baháʼ in the Abjad numerals, Abjad notation has a value of 9, and a 9-pointed star is used to Baháʼí symbols, symbolize the religion. *The number 9 is revered in Hinduism and considered a complete, perfected and divine number because it represents the end of a cycle in the decimal system, which originated from the Indian subcontinent as early as 30th century BC, 3000 BC. *In Buddhism, Gautama Buddha was believed to have nine virtues, which he was (1) Accomplished, (2) Perfectly Enlightened, (3) Endowed with knowledge and Conduct or Practice, (4) Well-gone or Well-spoken, (5) the Knower of worlds, (6) the Guide Unsurpassed of men to be tamed, (7) the Teacher of gods and men, (8) Enlightened, and (9) Blessed. *Important Buddhist rituals usually involve nine monks. *The first nine days of the Hebrew calendar, Hebrew month of Av (month), Av are collectively known as "The Nine Days" (''Tisha HaYamim''), and are a period of semi-mourning leading up to Tisha B'Av, the ninth day of Av on which both Temple in Jerusalem, Temples in Jerusalem were destroyed. *Nine is a significant number in Norse Mythology.

hung himself on an ash tree for nine days to learn the runes. *The Fourth Way Enneagram is one system of knowledge which shows the correspondence between the 9 integers and the circle. *In the Christian angelic hierarchy there are 9 choirs of angels. *Ramadan (calendar month), Ramadan, the month of fasting and prayer, is the ninth month of the Islamic calendar. *Tian's Trigram Number, of Feng Shui, in Taoism. *In Christianity there are nine Fruit of the Holy Spirit which followers are expected to have: love, joy, peace, forbearance, patience, kindness, Good and evil, goodness, faithfulness, gentleness, and self-control. *The Bible recorded that Christ died at the 9th hour of the day (3 pm).

Science

Astronomy

*Before 2006 (when Pluto was Pluto#2006: IAU classification, officially designated as a non-planet), there were nine planets in the Solar System. *Messier object Messier 9, M9 is a magnitude 9.0 globular cluster in the constellation Ophiuchus. *The New General Catalogue]
object
NGC 9, a spiral galaxy in the constellation Pegasus (constellation), Pegasus.

Chemistry

*The purity of chemicals (see Nine (purity)). *Nine is the atomic number of fluorine.

Physiology

A human pregnancy normally lasts nine months, the basis of Naegele's rule.

Psychology

Common terminal digit in psychological pricing.

Sports

*Nine-ball is the standard professional pocket billiards variant played in the United States. *In association football (soccer), the centre-forward/striker traditionally (since at least the fifties) wears the number 9 shirt. *In baseball: **There are nine players on the field including the pitcher. **There are nine innings in a standard game. **9 represents the right fielder's position. **''NINE: A Journal of Baseball History and Culture'', published by the University of Nebraska Press *In rugby league, the jersey number assigned to the Hooker (rugby league), hooker in most competitions. (An exception is the Super League, which uses static squad numbering.) *In rugby union, the number worn by the starting Scrum-half (rugby union), scrum-half.

Technology

*ISO 9 is the International Organization for Standardization, ISO's standard for the transliteration of Cyrillic characters into Latin characters *In the Rich Text Format specification, 9 is the language code for the English language. All codes for regional variants of English are congruent to 9 mod 256. *The9 Limited (owner o
the9.com
is a company in the video-game industry, including former ties to the extremely popular MMORPG World of Warcraft.

Music

*"Revolution 9", a sound collage which appears on The Beatles' eponymous 1968 album The Beatles (album), ''The Beatles'' (aka ''The White Album''), prominently features a loop of a man's voice repeating the phrase "Number nine". *There are 9 semitones in a Major 6th interval in music. *There was a Curse of the ninth, superstition among some notable classical music composers that they would die after completing their ninth symphony. Some composers who died after composing their ninth symphony include Ludwig van Beethoven, Anton Bruckner, Antonin Dvorak and Gustav Mahler.

Evolution of the Arabic digit

Mathematics

In decimal

List of basic calculations

Alphabets and codes

Culture and mythology

Indian culture

Chinese culture

Ancient Egypt

European culture

Greek mythology

Mesoamerican mythology

Aztec mythology

Mayan mythology

Anthropology

Idioms

Society

Technique

Pseudoscience

Literature

Organizations

Places and thoroughfares

Religion and philosophy

Science

Astronomy

Chemistry

Physiology

Psychology

Sports

Technology

Music

See also

References

Further reading