1 (one, unit, unity) is a
number representing a single or the only
entity. 1 is also a
numerical digit and represents a single
unit of
counting
Counting is the process of determining the number of elements of a finite set of objects, i.e., determining the size of a set. The traditional way of counting consists of continually increasing a (mental or spoken) counter by a unit for every elem ...
or
measurement. For example, a
line segment of ''unit length'' is a line segment of
length 1. In conventions of sign where zero is considered neither positive nor negative, 1 is the first and smallest
positive integer.
It is also sometimes considered the first of the
infinite sequence of
natural numbers, followed by
2, although by other definitions 1 is the second natural number, following
0.
The fundamental mathematical property of 1 is to be a
multiplicative identity, meaning that any number multiplied by 1 equals the same number. Most if not all properties of 1 can be deduced from this. In advanced mathematics, a multiplicative identity is often denoted 1, even if it is not a number. 1 is by convention not considered a
prime number; this was not universally accepted until the mid-20th century. Additionally, 1 is the smallest possible difference between two distinct
natural numbers.
The unique mathematical properties of the number have led to its unique uses in other fields, ranging from science to sports. It commonly denotes the first, leading, or top thing in a group.
Etymology
The word ''one'' can be used as a noun, an adjective, and a pronoun.
It comes from the English word ''an'',
which comes from the Proto-Germanic root .
The Proto-Germanic root comes from the Proto-Indo-European root ''*oi-no-''.
Compare the Proto-Germanic root to
Old Frisian ''an'',
Gothic
Gothic or Gothics may refer to:
People and languages
*Goths or Gothic people, the ethnonym of a group of East Germanic tribes
**Gothic language, an extinct East Germanic language spoken by the Goths
**Crimean Gothic, the Gothic language spoken b ...
''ains'',
Danish
Danish may refer to:
* Something of, from, or related to the country of Denmark
People
* A national or citizen of Denmark, also called a "Dane," see Demographics of Denmark
* Culture of Denmark
* Danish people or Danes, people with a Danish ance ...
''en'',
Dutch ''een'',
German
German(s) may refer to:
* Germany (of or related to)
**Germania (historical use)
* Germans, citizens of Germany, people of German ancestry, or native speakers of the German language
** For citizens of Germany, see also German nationality law
**Ge ...
''eins'' and
Old Norse ''einn''.
Compare the Proto-Indo-European root ''*oi-no-'' (which means "one, single"
) to
Greek ''oinos'' (which means "ace" on dice
),
Latin ''unus'' (one
),
Old Persian
Old Persian is one of the two directly attested Old Iranian languages (the other being Avestan language, Avestan) and is the ancestor of Middle Persian (the language of Sasanian Empire). Like other Old Iranian languages, it was known to its native ...
,
Old Church Slavonic ''-inu'' and ''ino-'',
Lithuanian
Lithuanian may refer to:
* Lithuanians
* Lithuanian language
* The country of Lithuania
* Grand Duchy of Lithuania
* Culture of Lithuania
* Lithuanian cuisine
* Lithuanian Jews as often called "Lithuanians" (''Lita'im'' or ''Litvaks'') by other Jew ...
''vienas'',
Old Irish ''oin'' and
Breton ''un'' (one
).
As a number
One, sometimes referred to as unity,
is the first non-zero
natural number. It is thus the
integer after
zero
0 (zero) is a number representing an empty quantity. In place-value notation such as the Hindu–Arabic numeral system, 0 also serves as a placeholder numerical digit, which works by multiplying digits to the left of 0 by the radix, usuall ...
.
Any number multiplied by one remains that number, as one is the
identity
Identity may refer to:
* Identity document
* Identity (philosophy)
* Identity (social science)
* Identity (mathematics)
Arts and entertainment Film and television
* ''Identity'' (1987 film), an Iranian film
* ''Identity'' (2003 film), an ...
for
multiplication. As a result, 1 is its own
factorial
In mathematics, the factorial of a non-negative denoted is the product of all positive integers less than or equal The factorial also equals the product of n with the next smaller factorial:
\begin
n! &= n \times (n-1) \times (n-2) ...
, its own
square and
square root, its own
cube and
cube root
In mathematics, a cube root of a number is a number such that . All nonzero real numbers, have exactly one real cube root and a pair of complex conjugate cube roots, and all nonzero complex numbers have three distinct complex cube roots. ...
, and so on. One is also the result of the
empty product, as any number multiplied by one is itself. It is also the only natural number that is neither
composite
Composite or compositing may refer to:
Materials
* Composite material, a material that is made from several different substances
** Metal matrix composite, composed of metal and other parts
** Cermet, a composite of ceramic and metallic materials ...
nor
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 ...
with respect to
division, but is instead considered a
unit (meaning of
ring theory).
As a digit
The glyph used today in the Western world to represent the number 1, a vertical line, often with a
serif
In typography, a serif () is a small line or stroke regularly attached to the end of a larger stroke in a letter or symbol within a particular font or family of fonts. A typeface or "font family" making use of serifs is called a serif typeface ( ...
at the top and sometimes a short horizontal line at the bottom, traces its roots back to the
Brahmic
The Brahmic scripts, also known as Indic scripts, are a family of abugida writing systems. They are used throughout the Indian subcontinent, Southeast Asia and parts of East Asia. They are descended from the Brahmi script of ancient In ...
script of ancient India, where it was a simple vertical line. It was transmitted to Europe via
the Maghreb and Andalusia during the Middle Ages, through scholarly works written in
Arabic
Arabic (, ' ; , ' or ) is a Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C. E.Watson; Walte ...
.
In some countries, the serif at the top is sometimes extended into a long upstroke, sometimes as long as the vertical line, which can lead to confusion with the glyph used for
seven in other countries. In styles in which the digit 1 is written with a long upstroke, the digit 7 is often written with a horizontal stroke through the vertical line, to disambiguate them. Styles that do not use the long upstroke on digit 1 usually do not use the horizontal stroke through the vertical of the digit 7 either.
While the shape of the character for the digit 1 has an
ascender in most modern
typefaces, in typefaces with
text figures, the glyph usually is of
x-height, as, for example, in
.
Many older typewriters lack a separate key for ''1'', using the lowercase letter ''l'' or uppercase ''I'' instead. It is possible to find cases when the uppercase ''J'' is used, though it may be for decorative purposes. In some typefaces, different glyphs are used for I and 1, but the numeral 1 resembles a
small caps version of I, with parallel serifs at top and bottom, with the capital I being full-height.
Mathematics
Definitions
Mathematically, 1 is:
*in
arithmetic
Arithmetic () is an elementary part of mathematics that consists of the study of the properties of the traditional operations on numbers—addition, subtraction, multiplication, division, exponentiation, and extraction of roots. In the 19th c ...
(
algebra
Algebra () is one of the broad areas of mathematics. Roughly speaking, algebra is the study of mathematical symbols and the rules for manipulating these symbols in formulas; it is a unifying thread of almost all of mathematics.
Elementary a ...
) and
calculus
Calculus, originally called infinitesimal calculus or "the calculus of infinitesimals", is the mathematical study of continuous change, in the same way that geometry is the study of shape, and algebra is the study of generalizations of arithm ...
, the
natural number that follows
0 and the multiplicative
identity element
In mathematics, an identity element, or neutral element, of a binary operation operating on a set is an element of the set that leaves unchanged every element of the set when the operation is applied. This concept is used in algebraic structures ...
of the
integers,
real numbers and
complex numbers;
*more generally, in
algebra
Algebra () is one of the broad areas of mathematics. Roughly speaking, algebra is the study of mathematical symbols and the rules for manipulating these symbols in formulas; it is a unifying thread of almost all of mathematics.
Elementary a ...
, the multiplicative identity (also called ''unity''), usually of a
group
A group is a number of persons or things that are located, gathered, or classed together.
Groups of people
* Cultural group, a group whose members share the same cultural identity
* Ethnic group, a group whose members share the same ethnic ide ...
or a
ring
Ring may refer to:
* Ring (jewellery), a round band, usually made of metal, worn as ornamental jewelry
* To make a sound with a bell, and the sound made by a bell
:(hence) to initiate a telephone connection
Arts, entertainment and media Film and ...
.
Formalizations of the natural numbers have their own representations of 1. In the
Peano axioms, 1 is the
successor
Successor may refer to:
* An entity that comes after another (see Succession (disambiguation))
Film and TV
* ''The Successor'' (film), a 1996 film including Laura Girling
* ''The Successor'' (TV program), a 2007 Israeli television program Musi ...
of 0. In ''
Principia Mathematica
The ''Principia Mathematica'' (often abbreviated ''PM'') is a three-volume work on the foundations of mathematics written by mathematician–philosophers Alfred North Whitehead and Bertrand Russell and published in 1910, 1912, and 1913. ...
'', it is defined as the set of all
singletons (sets with one element), and in the
Von Neumann cardinal assignment
The von Neumann cardinal assignment is a cardinal assignment that uses ordinal numbers. For a well-orderable set ''U'', we define its cardinal number to be the smallest ordinal number equinumerous to ''U'', using the von Neumann definition of an or ...
of natural numbers, it is defined as 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 ...
.
In a multiplicative
group
A group is a number of persons or things that are located, gathered, or classed together.
Groups of people
* Cultural group, a group whose members share the same cultural identity
* Ethnic group, a group whose members share the same ethnic ide ...
or
monoid
In abstract algebra, a branch of mathematics, a monoid is a set equipped with an associative binary operation and an identity element. For example, the nonnegative integers with addition form a monoid, the identity element being 0.
Monoids a ...
, the
identity element
In mathematics, an identity element, or neutral element, of a binary operation operating on a set is an element of the set that leaves unchanged every element of the set when the operation is applied. This concept is used in algebraic structures ...
is sometimes denoted 1, but ''e'' (from the German ''Einheit'', "unity") is also traditional. However, 1 is especially common for the multiplicative identity of a ring, i.e., when an addition and 0 are also present. When such a ring has
characteristic ''n'' not equal to 0, the element called 1 has the property that (where this 0 is the additive identity of the ring). Important examples are
finite fields.
By definition, 1 is the
magnitude
Magnitude may refer to:
Mathematics
*Euclidean vector, a quantity defined by both its magnitude and its direction
*Magnitude (mathematics), the relative size of an object
*Norm (mathematics), a term for the size or length of a vector
*Order of ...
,
absolute value
In mathematics, the absolute value or modulus of a real number x, is the non-negative value without regard to its sign. Namely, , x, =x if is a positive number, and , x, =-x if x is negative (in which case negating x makes -x positive), an ...
, or
norm
Naturally occurring radioactive materials (NORM) and technologically enhanced naturally occurring radioactive materials (TENORM) consist of materials, usually industrial wastes or by-products enriched with radioactive elements found in the envi ...
of a
unit complex number,
unit vector
In mathematics, a unit vector in a normed vector space is a vector (often a spatial vector) of length 1. A unit vector is often denoted by a lowercase letter with a circumflex, or "hat", as in \hat (pronounced "v-hat").
The term ''direction vec ...
, and a
unit matrix
In linear algebra, the identity matrix of size n is the n\times n square matrix with ones on the main diagonal and zeros elsewhere.
Terminology and notation
The identity matrix is often denoted by I_n, or simply by I if the size is immaterial or ...
(more usually called an identity matrix). Note that the term ''unit matrix'' is sometimes used to mean something
quite different.
By definition, 1 is the
probability of an event that is absolutely or
almost certain
In probability theory, an event is said to happen almost surely (sometimes abbreviated as a.s.) if it happens with probability 1 (or Lebesgue measure 1). In other words, the set of possible exceptions may be non-empty, but it has probability 0. ...
to occur.
In
category theory
Category theory is a general theory of mathematical structures and their relations that was introduced by Samuel Eilenberg and Saunders Mac Lane in the middle of the 20th century in their foundational work on algebraic topology. Nowadays, cate ...
, 1 is sometimes used to denote the
terminal object of a
category
Category, plural categories, may refer to:
Philosophy and general uses
*Categorization, categories in cognitive science, information science and generally
*Category of being
* ''Categories'' (Aristotle)
*Category (Kant)
*Categories (Peirce)
*C ...
.
In
number theory, 1 is the value of
Legendre's constant
Legendre's constant is a mathematical constant occurring in a formula conjectured by Adrien-Marie Legendre to capture the asymptotic behavior of the prime-counting function \pi(x). Its value is now known to be 1.
Examination of available n ...
, which was introduced in 1808 by
Adrien-Marie Legendre
Adrien-Marie Legendre (; ; 18 September 1752 – 9 January 1833) was a French mathematician who made numerous contributions to mathematics. Well-known and important concepts such as the Legendre polynomials and Legendre transformation are named ...
in expressing the
asymptotic behavior
In mathematical analysis, asymptotic analysis, also known as asymptotics, is a method of describing limiting behavior.
As an illustration, suppose that we are interested in the properties of a function as becomes very large. If , then as beco ...
of the
prime-counting function. Legendre's constant was originally conjectured to be approximately 1.08366, but was proven to equal exactly 1 in 1899.
Properties
Tallying is often referred to as "base 1", since only one mark – the tally itself – is needed. This is more formally referred to as a
unary numeral system. Unlike
base 2 or
base 10, this is not a
positional notation
Positional notation (or place-value notation, or positional numeral system) usually denotes the extension to any base of the Hindu–Arabic numeral system (or decimal system). More generally, a positional system is a numeral system in which the ...
.
Since the base 1 exponential function (1
''x'') always equals 1, its
inverse
Inverse or invert may refer to:
Science and mathematics
* Inverse (logic), a type of conditional sentence which is an immediate inference made from another conditional sentence
* Additive inverse (negation), the inverse of a number that, when a ...
does not exist (which would be called the
logarithm base 1 if it did exist).
There are two ways to write the real number 1 as a
recurring decimal: as 1.000..., and as
0.999.... 1 is the first
figurate number of every kind, such as
triangular number
A triangular number or triangle number counts objects arranged in an equilateral triangle. Triangular numbers are a type of figurate number, other examples being square numbers and cube numbers. The th triangular number is the number of dots in ...
,
pentagonal number and
centered hexagonal number, to name just a few.
In many mathematical and engineering problems, numeric values are typically ''normalized'' to fall within the
unit interval from 0 to 1, where 1 usually represents the maximum possible value in the range of parameters. Likewise,
vectors are often normalized into
unit vector
In mathematics, a unit vector in a normed vector space is a vector (often a spatial vector) of length 1. A unit vector is often denoted by a lowercase letter with a circumflex, or "hat", as in \hat (pronounced "v-hat").
The term ''direction vec ...
s (i.e., vectors of magnitude one), because these often have more desirable properties. Functions, too, are often normalized by the condition that they have
integral one, maximum value one, or
square integral one, depending on the application.
Because of the multiplicative identity, if ''f''(''x'') is a
multiplicative function
In number theory, a multiplicative function is an arithmetic function ''f''(''n'') of a positive integer ''n'' with the property that ''f''(1) = 1 and
f(ab) = f(a)f(b) whenever ''a'' and ''b'' are coprime.
An arithmetic function ''f''(''n'') is ...
, then ''f''(1) must be equal to 1.
It is also the first and second number in the
Fibonacci sequence (0 being the zeroth) and is the first number in many other
mathematical sequences.
The definition of a
field
Field may refer to:
Expanses of open ground
* Field (agriculture), an area of land used for agricultural purposes
* Airfield, an aerodrome that lacks the infrastructure of an airport
* Battlefield
* Lawn, an area of mowed grass
* Meadow, a grass ...
requires that 1 must not be equal to
0. Thus, there are no fields of characteristic 1. Nevertheless, abstract algebra can consider the
field with one element, which is not a singleton and is not a set at all.
1 is the most common leading digit in many sets of data, a consequence of
Benford's law
Benford's law, also known as the Newcomb–Benford law, the law of anomalous numbers, or the first-digit law, is an observation that in many real-life sets of numerical data, the leading digit is likely to be small.Arno Berger and Theodore ...
.
1 is the only known
Tamagawa number In mathematics, the Tamagawa number \tau(G) of a semisimple algebraic group defined over a global field is the measure of G(\mathbb)/G(k), where \mathbb is the adele ring of . Tamagawa numbers were introduced by , and named after him by .
Tsuneo ...
for a simply connected algebraic group over a number field.
The
generating function
In mathematics, a generating function is a way of encoding an infinite sequence of numbers () by treating them as the coefficients of a formal power series. This series is called the generating function of the sequence. Unlike an ordinary serie ...
that has all coefficients 1 is given by
This power series converges and has finite value
if and only if .
Primality
1 is by convention neither a
prime number nor a
composite number, but a
unit (meaning of
ring theory) like −1 and, in the
Gaussian integers, ''
i'' and −''i''.
The
fundamental theorem of arithmetic guarantees
unique factorization over the integers only up to units. For example, , but if units are included, is also equal to, say, among infinitely many similar "factorizations".
1 appears to meet the naïve definition of a prime number, being evenly divisible only by 1 and itself (also 1). As such, some mathematicians considered it a prime number as late as the middle of the 20th century, but mathematical consensus has generally and since then universally been to exclude it for a variety of reasons (such as complicating the fundamental theorem of arithmetic and other theorems related to prime numbers).
1 is the only positive integer divisible by exactly one positive integer, whereas prime numbers are divisible by exactly two positive integers, composite numbers are divisible by more than two positive integers, and
zero
0 (zero) is a number representing an empty quantity. In place-value notation such as the Hindu–Arabic numeral system, 0 also serves as a placeholder numerical digit, which works by multiplying digits to the left of 0 by the radix, usuall ...
is divisible by all positive integers.
Table of basic calculations
In technology
* The
resin identification code used in recycling to identify
polyethylene terephthalate.
*The
ITU
The International Telecommunication Union is a specialized agency of the United Nations responsible for many matters related to information and communication technologies. It was established on 17 May 1865 as the International Telegraph Union ...
country code for the
North American Numbering Plan area, which includes the United States, Canada, and parts of the Caribbean.
*A
binary code
A binary code represents text, computer processor instructions, or any other data using a two-symbol system. The two-symbol system used is often "0" and "1" from the binary number system. The binary code assigns a pattern of binary digits, also ...
is a sequence of 1 and
0 that is used in
computers for representing any kind of
data.
*In many physical devices, 1 represents the value for "on", which means that electricity is flowing.
*The numerical value of
true in many programming languages.
*1 is the
ASCII
ASCII ( ), abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because of ...
code of "
Start of Header".
In science
*
Dimensionless quantities
A dimensionless quantity (also known as a bare quantity, pure quantity, or scalar quantity as well as quantity of dimension one) is a quantity to which no physical dimension is assigned, with a corresponding SI unit of measurement of one (or 1) ...
are also known as quantities of dimension one.
*1 is the atomic number of
hydrogen.
*+1 is the
electric charge of
positron
The positron or antielectron is the antiparticle or the antimatter counterpart of the electron. It has an electric charge of +1 '' e'', a spin of 1/2 (the same as the electron), and the same mass as an electron. When a positron collides ...
s and protons.
*Group 1 of the
periodic table
The periodic table, also known as the periodic table of the (chemical) elements, is a rows and columns arrangement of the chemical elements. It is widely used in chemistry, physics, and other sciences, and is generally seen as an icon of ch ...
consists of the
alkali metals
The alkali metals consist of the chemical elements lithium (Li), sodium (Na), potassium (K),The symbols Na and K for sodium and potassium are derived from their Latin names, ''natrium'' and ''kalium''; these are still the origins of the names ...
.
*Period 1 of the periodic table consists of just two elements,
hydrogen and
helium.
*The dwarf planet
Ceres
Ceres most commonly refers to:
* Ceres (dwarf planet), the largest asteroid
* Ceres (mythology), the Roman goddess of agriculture
Ceres may also refer to:
Places
Brazil
* Ceres, Goiás, Brazil
* Ceres Microregion, in north-central Goiás ...
has the minor-planet designation 1 Ceres because it was the first asteroid to be discovered.
*The Roman numeral I often stands for the first-discovered satellite of a
planet or
minor planet
According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''mino ...
(such as Neptune I, a.k.a.
Triton
Triton commonly refers to:
* Triton (mythology), a Greek god
* Triton (moon), a satellite of Neptune
Triton may also refer to:
Biology
* Triton cockatoo, a parrot
* Triton (gastropod), a group of sea snails
* ''Triton'', a synonym of ''Triturus'' ...
). For some earlier discoveries, the Roman numerals originally reflected the increasing distance from the primary instead.
In philosophy
In the philosophy of
Plotinus
Plotinus (; grc-gre, Πλωτῖνος, ''Plōtînos''; – 270 CE) was a philosopher in the Hellenistic tradition, born and raised in Roman Egypt. Plotinus is regarded by modern scholarship as the founder of Neoplatonism. His teacher wa ...
(and that of other
neoplatonists),
The One is the ultimate reality and source of all existence.
Philo of Alexandria (20 BC – AD 50) regarded the number one as God's number, and the basis for all numbers ("De Allegoriis Legum," ii.12
.66.
The Neopythagorean philosopher
Nicomachus of Gerasa affirmed that one is not a number, but the source of number. He also believed the
number two is the embodiment of the origin of
otherness. His
number theory was recovered by
Boethius
Anicius Manlius Severinus Boethius, commonly known as Boethius (; Latin: ''Boetius''; 480 – 524 AD), was a Roman senator, consul, ''magister officiorum'', historian, and philosopher of the Early Middle Ages. He was a central figure in the tra ...
in his Latin translation of Nicomachus's treatise ''
Introduction to Arithmetic
The book ''Introduction to Arithmetic'' ( grc-gre, Ἀριθμητικὴ εἰσαγωγή, ''Arithmetike eisagoge'') is the only extant work on mathematics by Nicomachus (60–120 AD).
Summary
The work contains both philosophical prose and ...
''.
In sports
In many professional sports, the number 1 is assigned to the player who is first or leading in some respect, or otherwise important; the number is printed on his sports uniform or equipment. This is the
pitcher in
baseball
Baseball is a bat-and-ball sport played between two teams of nine players each, taking turns batting and fielding. The game occurs over the course of several plays, with each play generally beginning when a player on the fielding tea ...
, the
goalkeeper
In many team sports which involve scoring goals, the goalkeeper (sometimes termed goaltender, netminder, GK, goalie or keeper) is a designated player charged with directly preventing the opposing team from scoring by blocking or intercepting ...
in
association football (soccer), the starting
fullback in most of
rugby league, the starting
loosehead prop in
rugby union and the previous year's world champion in
Formula One. 1 may be the lowest possible player number, like in the American–Canadian
National Hockey League (NHL) since the 1990s or in
American football
American football (referred to simply as football in the United States and Canada), also known as gridiron, is a team sport played by two teams of eleven players on a rectangular field with goalposts at each end. The offense, the team with ...
.
In other fields
*''Number One'' is
Royal Navy
The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against ...
informal usage for the chief executive officer of a ship, the captain's deputy responsible for discipline and all normal operation of a ship and its crew.
*1 is the value of an
ace
An ace is a playing card, die or domino with a single pip. In the standard French deck, an ace has a single suit symbol (a heart, diamond, spade, or club) located in the middle of the card, sometimes large and decorated, especially in the ca ...
in many playing card games, such as
cribbage
Cribbage, or crib, is a card game, traditionally for two players, that involves playing and grouping cards in combinations which gain points. It can be adapted for three or four players.
Cribbage has several distinctive features: the cribbag ...
.
*
List of highways numbered 1
The following highways are numbered 1.
For roads numbered A1, see list of A1 roads.
For roads numbered B1, see list of B1 roads.
For roads numbered M1, see List of M1 roads.
For roads numbered N1, see list of N1 roads.
For roads numbere ...
*
List of public transport routes numbered 1
In public transport, Route 1 may refer to:
*Route 1 (MTA Maryland), a bus route in Baltimore, Maryland
* Barcelona Metro line 1
*Line 1 (Beijing Subway)
*Line 1 (Hangzhou Metro)
* Citybus Route 1 in Hong Kong
* KMB Route 1 in Hong Kong
*London Bus ...
*1 is often used to denote the
Gregorian calendar month of
January.
*
1 CE
__NOTOC__
AD 1 or 1 CE is the epoch year for the Anno Domini (AD) Christian calendar era and also the 1st year of the Common Era (CE) and the 1st millennium and of the 1st century of the Christian and the common era. It was a common year starti ...
, the first year of the
Common Era
Common Era (CE) and Before the Common Era (BCE) are year notations for the Gregorian calendar (and its predecessor, the Julian calendar), the world's most widely used calendar era. Common Era and Before the Common Era are alternatives to the or ...
*01, the former dialling code for
Greater London (now 020)
*For Pythagorean
numerology (a
pseudoscience), the number 1 is the number that means beginning, new beginnings, new cycles, it is a unique and absolute number.
*
PRS One
The PRS One is a German single-place paraglider that was produced by Pilots Right Stuff (PRS) of Brannenburg, starting in 2000. It was designed with outside contract assistance. The glider is now out of production.
Design and development
The ...
, a German paraglider design
*+1 is the code for international telephone calls to countries in the
North American Numbering Plan.
* In some countries, a
street address of "1" is considered prestigious and developers will attempt to obtain such an address for a building, to the point of lobbying for a street or portion of a street to be renamed, even if this makes the address less useful for wayfinding. The construction of a new street to serve the development may also provide the possibility of a "1" address. An example of such an address is the
Apple Campus
The Apple Campus is the former corporate headquarters of Apple Inc. from 1993 until 2017, when it was largely replaced by Apple Park, though it is still used by Apple as office and lab space. The campus is located at 1 Infinite Loop in Cupertin ...
, located at 1 Infinite Loop,
Cupertino, California.
See also
*
−1
In mathematics, −1 (also known as negative one or minus one) is the additive inverse of 1, that is, the number that when added to 1 gives the additive identity element, 0. It is the negative integer greater than negative two (−2) and less t ...
*
+1 (disambiguation)
*
List of mathematical constants
*
One (word)
''One'' is an English language, gender-neutral, indefinite pronoun that means, roughly, "a person". For purposes of verb agreement it is a third-person singular pronoun, though it sometimes appears with first- or second-person reference. It is ...
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Root of unity
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List of highways numbered 1
The following highways are numbered 1.
For roads numbered A1, see list of A1 roads.
For roads numbered B1, see list of B1 roads.
For roads numbered M1, see List of M1 roads.
For roads numbered N1, see list of N1 roads.
For roads numbere ...
References
External links
The Number 1The Positive Integer 1
{{DEFAULTSORT:1 (Number)
Integers