8 (eight) is the

_{8} lattice. Even positive definite unimodular lattices exist only in dimensions divisible by 8.
A figure 8 is the common name of a

object

NGC 8, a double star in the constellation Pegasus (constellation), Pegasus. * Since the demotion of Pluto to a dwarf planet on 24 August 2006, in our Solar System, eight of the bodies orbiting the Sun are considered to be planets.

^{8} is yotta (Y), and for its reciprocal, yocto (y).
* In liquid measurement (United States customary units), there are eight fluid ounces in a Cup (volume), cup, eight pints in a gallon and eight tablespoonfuls in a gill (volume), gill.
* There are eight furlongs in a mile.
* The clove, an old English units#Avoirdupois, English unit of weight, was equal to eight pounds when measuring cheese.
* An eight may be an article of clothing of the eighth clothing sizes, size.
* Force eight is the first wind strength attributed to a gale on the Beaufort scale when announced on a Shipping Forecast.

"''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. *There are eight Guardians of the directions known as ''Astha-dikpalas''. *There are eight Hindu monasteries established by saint Madhvacharya in Udupi, India popularly known as the ''Ashta Mathas of Udupi''.

by Richard Williams, ''The Guardian'', published 9 August 2008 * is also considered a lucky number in Japan, 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, 8 is the number of building, and in some theories, also the number of destruction.

The Octonions

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

natural number
File:Three Baskets.svg, Natural numbers can be used for counting (one apple, two apples, three apples, ...)
In mathematics, the natural numbers are those numbers used for counting (as in "there are ''six'' coins on the table") and total order, o ...

following and preceding .
In mathematics

8 is: * acomposite number
A composite number is a positive integer
In mathematics
Mathematics (from Ancient Greek, Greek: ) includes the study of such topics as quantity (number theory), mathematical structure, structure (algebra), space (geometry), and calculu ...

, its proper divisor
In mathematics
Mathematics (from Ancient Greek, Greek: ) includes the study of such topics as quantity (number theory), mathematical structure, structure (algebra), space (geometry), and calculus, change (mathematical analysis, analysis). ...

s being , , and . It is twice 4 or four times 2.
* a power of two
Visualization of powers of two from 1 to 1024 (20 to 210)
A power of two is a number of the form where is an integer
An integer (from the Latin wikt:integer#Latin, ''integer'' meaning "whole") is colloquially defined as a number that can b ...

, 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 (mathematics), 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 ...

nor semiprime
In mathematics
Mathematics (from Ancient Greek, Greek: ) includes the study of such topics as quantity (number theory), mathematical structure, structure (algebra), space (geometry), and calculus, change (mathematical analysis, analysis). It h ...

.
* the base of the octal
The octal , or oct for short, is the -8 number system, and uses the 0 to 7, that is to say 10 represents 8 in decimal and 100 represents 64 in decimal. However, English uses a number language system, hence a true octal system might use differe ...

number system, which is mostly used with computer
A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automatically. Modern computers can perform generic sets of operations known as Computer program, programs. These programs enable compu ...

s. In octal, one digit represents three bit
The bit is a basic unit of information in computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes and development of both ...

s. In modern computers, a byte
The byte is a unit of digital information that most commonly consists of eight bit
The bit is a basic unit of information in computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It ...

is a grouping of eight bits, also called an octet
Octet may refer to:
Music
* Octet (music)
In music
Music is the art of arranging sounds in time to produce a composition through the elements of melody, harmony, rhythm, and timbre. It is one of the universal cultural
Culture () is ...

.
* a Fibonacci number
In mathematics, the Fibonacci numbers, commonly denoted , form a sequence
In mathematics, a sequence is an enumerated collection of objects in which repetitions are allowed and order theory, order matters. Like a Set (mathematics), set, it cont ...

, 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
Mathematics (from Ancient Greek, Greek: ) includes the study of such topics as quantity (number theory), mathematical structure, structure (algebra), space (geometry), and calculus, change (mathematical analysis, analysis). It ...

that is one less than another perfect power, by Mihăilescu's Theorem.
* the order of the smallest non-abelian group all of whose subgroups are normal.
* the dimension of the octonion
In mathematics
Mathematics (from Ancient Greek, Greek: ) includes the study of such topics as quantity (number theory), mathematical structure, structure (algebra), space (geometry), and calculus, change (mathematical analysis, analysis). It ...

s and is the highest possible dimension of a normed division algebraIn mathematics
Mathematics (from Ancient Greek, Greek: ) includes the study of such topics as quantity (number theory), mathematical structure, structure (algebra), space (geometry), and calculus, change (mathematical analysis, analysis). It ha ...

.
* 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
A numeral system (or system of numeration) is a writing system
A writing system is a method of visually representing verbal communication
Communication (from Latin ''communicare'', meaning "to share") is t ...

, 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
In mathematics and digital electronics, a binary number is a number
A number is a mathematical object used to counting, count, measurement, measure, and nominal ...

.
There are a total of eight convex deltahedra.
A polygon
In geometry, a polygon () is a plane (mathematics), plane Shape, 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 (mathematic ...

with eight sides is an octagon
In , an octagon (from the ὀκτάγωνον ''oktágōnon'', "eight angles") is an eight-sided or 8-gon.
A '' octagon'' has and can also be constructed as a quasiregular , t, which alternates two types of edges. A truncated octagon, t is ...

. Figurate numberThe 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 (including eight) are called octagonal number
An octagonal number is a figurate numberThe 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 (polyhedr ...

s.
A polyhedron
In geometry
Geometry (from the grc, γεωμετρία; ' "earth", ' "measurement") is, with , one of the oldest branches of . It is concerned with properties of space that are related with distance, shape, size, and relative position o ...

with eight faces is an octahedron
In geometry, an octahedron (plural: octahedra, octahedrons) is a polyhedron with eight faces, twelve edges, and six vertices. The term is most commonly used to refer to the regular octahedron, a Platonic solid composed of eight equilateral tria ...

. A cuboctahedron
A cuboctahedron is a polyhedron with 8 triangular faces and 6 square faces. A cuboctahedron has 12 identical vertex (geometry), vertices, with 2 triangles and 2 squares meeting at each, and 24 identical edge (geometry), edges, each separating a tri ...

has as faces six equal squares and eight equal regular triangles.
A cube
In geometry, a cube is a three-dimensional space, three-dimensional solid object bounded by six square (geometry), square faces, Facet (geometry), facets or sides, with three meeting at each vertex (geometry), vertex.
The cube is the only Reg ...

has eight vertices.
Sphenic numberIn number theory, a sphenic number (from grc, σφήνα, 'wedge') is a positive integer that is the product of three distinct prime number
A prime number (or a prime) is a natural number greater than 1 that is not a Product (mathematics), pr ...

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
Mathematics (from Ancient Greek, Greek: ) includes the study of such topics as quantity (number theory), mathematical structure, structure (algebra), space (geometry), and calculus, change (mathematical analysis, analysis). It ...

. For example, if ''O''(∞) is the direct limit of the inclusions of real orthogonal groups
:$O(1)\backslash hookrightarrow\; O(2)\backslash hookrightarrow\backslash ldots\backslash hookrightarrow\; O(k)\backslash hookrightarrow\backslash ldots$,
then
:$\backslash pi\_(O(\backslash infty))\backslash cong\backslash pi\_(O(\backslash infty))$.
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
Mathematics (from Greek: ) includes the study of such topics as numbers ( and ), formulas and related structures (), shapes and spaces in which they are contained (), and quantities and their changes ( and ). There is no gen ...

of spheres and in the representation theory
Representation theory is a branch of mathematics that studies abstract algebra, abstract algebraic structures by ''representing'' their element (set theory), elements as linear transformations of vector spaces, and studies Module (mathematics), ...

of the rotation group
In mathematics
Mathematics (from Ancient Greek, Greek: ) includes the study of such topics as quantity (number theory), mathematical structure, structure (algebra), space (geometry), and calculus, change (mathematical analysis, analysis). It ...

s, the latter giving rise to the 8 by 8 spinor
In geometry and physics, spinors are elements of a complex numbers, complex vector space that can be associated with Euclidean space. Like Euclidean vector, geometric vectors and more general tensors, spinors linear transformation, transform line ...

ial chessboard. All of these properties are closely related to the properties of the octonion
In mathematics
Mathematics (from Ancient Greek, Greek: ) includes the study of such topics as quantity (number theory), mathematical structure, structure (algebra), space (geometry), and calculus, change (mathematical analysis, analysis). It ...

s.
The spin groupIn mathematics
Mathematics (from Ancient Greek, Greek: ) includes the study of such topics as quantity (number theory), mathematical structure, structure (algebra), space (geometry), and calculus, change (mathematical analysis, analysis). It ha ...

Spin(8) is the unique such group that exhibits the phenomenon of triality
133px, The automorphisms of the Dynkin diagram D4 give rise to triality in Spin(8).
In mathematics, triality is a relationship among three vector spaces, analogous to the duality (mathematics), duality relation between dual vector spaces. Most com ...

.
The lowest-dimensional even unimodular lattice
In geometry
Geometry (from the grc, γεωμετρία; ''wikt:γῆ, geo-'' "earth", ''wikt:μέτρον, -metron'' "measurement") is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space that ...

is the 8-dimensional Egeometric
Geometry (from the grc, γεωμετρία; '' geo-'' "earth", '' -metron'' "measurement") is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space that are related with distance, shape, size, ...

shape
A shape or figure is the form 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 plane shape, two-dimensional sh ...

, 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
Reconstruction may refer to:
Politics, history, and sociology
*Reconstruction (law), the transfer of a company's (or several companies') business to a new ...

''*ahto''
is a direct continuation of Proto-Indo-European
Proto-Indo-European (PIE) is the theorized common ancestor of the Indo-European language family
The Indo-European languages are a language family
A language is a structured system of communication used by humans, including speech ( ...

'' *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''.
The adjective ''octuple'' (Latin ''octu-plus'') may also be used as a noun, meaning "a set of eight items"; the diminutive ''octuplet'' is mostly used to refer to eight siblings delivered in one birth.
The Semitic numerals, Semitic numeral is based on a root ''*θmn-'', whence Akkadian ''smn-'', Arabic ''ṯmn-'', Hebrew ''šmn-'' etc.
The Chinese numeral, written (Standard Mandarin, Mandarin: ''bā''; Cantonese language, Cantonese: ''baat''), is from Old Chinese ''*priāt-'', ultimately from Sino-Tibetan :wikt:Appendix:Proto-Sino-Tibetan/b-r-gjat ~ b-g-rjat, ''b-r-gyat'' or ''b-g-ryat'' which also yielded Tibetan '':wikt:བརྒྱད, brgyat''.
It has been argued that, as the cardinal number is the highest number of item that can universally be The Magical Number Seven, Plus or Minus Two, 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 languages, Turkic words for "eight" are from a Proto-Turkic 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 languages, Finnic '':wikt:Appendix:Proto-Finnic/kakteksa, *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 modern Arabic numerals other than zero, originates with the Brahmi numerals. 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 :wikt:٨, ٨ (and also gave rise to the later Devanagari form :wikt:८, 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 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"). 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 typefaces, in typefaces with text figures the character for the digit 8 usually has an ascender (typography), ascender, as, for example, in . The infinity symbol ∞, 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 for "one thousand" CIƆ, or alternatively from the final Greek letter, ω.In science

Physics

* In nuclear physics, the second Magic number (physics), magic number. * In particle physics, the eightfold Way (physics), eightfold way is used to classify sub-atomic particles. * In statistical mechanics, the eight-vertex model has 8 possible configurations of arrows at each vertex.Astronomy

* Messier object Lagoon Nebula, M8, a magnitude 5.0 nebula in the constellation of Sagittarius (constellation), Sagittarius. * The New General Catalogue]object

NGC 8, a double star in the constellation Pegasus (constellation), Pegasus. * Since the demotion of Pluto to a dwarf planet on 24 August 2006, in our Solar System, eight of the bodies orbiting the Sun are considered to be planets.

Chemistry

* The atomic number of oxygen. * The most stable allotrope of a sulfur molecule is made of eight sulfur atoms arranged in a rhombic form. * The maximum number of electrons that can occupy a electron shell#Valence shells, valence shell. * The red pigment lycopene consists of eight isoprene units.Geology

* A disphenoid crystal is bounded by eight scalene triangles arranged in pairs. A ditetragonal prism in the tetragonal crystal system has eight similar faces whose alternate interfacial angles only are equal.Biology

* All spiders, and more generally all arachnids, have eight legs. Orb-weaver spiders of the cosmopolitan family Areneidae have eight similar eyes. * The octopus and its cephalopod relatives in genus Argonaut (animal), ''Argonauta'' have eight arms (tentacles). * Compound coelenterates of the subclass or order octocorallia, Alcyonaria have polyps with eight-branched tentacles and eight septa. * Sea anemones of genus ''Edwardsia'' have eight Mesentery#Invertebrate anatomy, mesenteries. * Animals of phylum Ctenophora swim by means of eight meridional bands of transverse ciliated plates, each plate representing a row of large modified cilia. * The Alypia octomaculata, eight-spotted forester (genus ''Alypia'', family Zygaenidae) is a diurnal moth having black wings with brilliant white spots. * The ascus in fungi of the class Ascomycota#Ascomycetes versus Ascomycetes, Ascomycetes, following nuclear fusion, bears within it typically eight ascospores. * Herbs of genus ''Coreopsis'' (tickseed) have showy flower heads with involucral bracts in two distinct series of eight each. * In human adult dentition there are eight teeth in each quadrant. The eighth tooth is the so-called wisdom tooth. * There are eight cervical nerves on each side in man and most mammals.Psychology

* There are eight Jungian cognitive functions, according to the MBTI models by John Beebe and Linda Berens. * Timothy Leary identified a 8-Circuit Model of Consciousness, hierarchy of eight levels of consciousness.In technology

* Abyte
The byte is a unit of digital information that most commonly consists of eight bit
The bit is a basic unit of information in computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It ...

is eight bit
The bit is a basic unit of information in computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes and development of both ...

s.
* Many (mostly historic) computer architectures are eight-bit, among them the Nintendo Entertainment System.
* Standard 8 mm film, Standard-8 and Super 8 mm film, Super-8 are 8 mm List of film formats, film formats.
* Video8, Hi8 and Digital8 are related 8 mm video formats.
* On most phones, the 8 key is associated with the letters T, U, and V, but on the BlackBerry it is the key for B, N, and X.
* An eight may refer to an eight-cylinder engine or automobile. A V8 engine is an internal combustion engine with eight cylinders configured in two banks (rows) of four forming a "V" when seen from the end.
* A figure-eight knot (so named for its configuration) is a kind of stopper knot.
* The number eight written in parentheses is the code for the musical note in Windows Live Messenger.
* In a seven-segment display, when an 8 is illuminated, all the display bulbs are on.
In measurement

* The SI prefix for 1000In culture

Currency

* Sailors and civilians alike from the 1500s onward referred to evenly divided parts of the Spanish dollar, Spanish Dollar as "pieces of eight", or "bits".Architecture

* Various types of buildings are usually eight-sided (octagonal), such as single-roomed gazebos and multi-roomed pagodas (descended from stupas; see religion section below). * Eight Glossary of architecture#C, caulicoles rise out of the leafage in a Corinthian order, Corinthian capital, ending in leaves that support the volutes.In religion, folk belief and divination

Hinduism

* Also known as Ashtha, Aṣṭa, or Ashta in Sanskrit, it is the number of wealth and abundance. * The Goddess of wealth and prosperity Lakshmi has eight forms which is known as Ashta Lakshmi 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. *There are eight Guardians of the directions known as ''Astha-dikpalas''. *There are eight Hindu monasteries established by saint Madhvacharya in Udupi, India popularly known as the ''Ashta Mathas of Udupi''.

Buddhism

* The Dharmacakra, a Buddhism, Buddhist symbol, has eight spokes. The Buddha's principal teaching—the Four Noble Truths—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). These are later (controversially) associated with the Eight Consciousnesses according to the Yogacara 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 falls on the 8th day of the 4th month of the Chinese calendar.Judaism

* The religious rite of brit milah (commonly known as circumcision) is held on a baby boy's eighth day of life. * Hanukkah is an eight-day Jewish holiday that starts on the 25th day of Kislev. * Shemini Atzeret (Hebrew language, Hebrew: "Eighth Day of Assembly") is a one-day Jewish holiday immediately following the seven-day holiday of Sukkot.Christianity

* The spiritual The eighth day (Christian), Eighth Day, because the number 7 refers to the days of the week (which repeat themselves). * The number of Beatitudes. * wikisource:Bible (King James)/1 Peter#3:20, 1 Peter 3:20 states that there were eight people on Noah's Ark. * The Antichrist is the eighth king in the Book of Revelation.Islam

* In Islam, eight is the number of angels carrying the Throne of God, throne of Allah in heaven. * The number of gates of heaven.Taoism

* Ba Gua * Ba Xian * baduanjin, Ba Duan JinOther

* In Wicca, there are eight Sabbats, festivals, seasons, or spokes in the Wheel of the Year. * In Ancient Egyptian mythology, the Ogdoad (Egyptian), Ogdoad represents the Ancient Egyptian creation myths, eight primordial deities of creation. * In Scientology there are eight dynamics of existence.As a lucky number

* The number eight is considered to be a Numbers in Chinese culture, lucky number in Chinese and other Asian cultures. Eight (; Chinese numerals#Numeral characters, accounting ; pinyin ''bā'') is considered a Numbers in Chinese culture#Eight, lucky number in Chinese culture because it sounds like the word meaning to generate wealth (; Pinyin: ''fā''). Property with the number 8 may be valued greatly by Chinese. For example, a Hong Kong Vehicle registration plate, number plate with the number 8 was sold for $640,000. The opening ceremony of the 2008 Summer Olympics, Summer Olympics in Beijing started at 8 seconds and 8 minutes past 8 pm (local time) on 8 August 2008."Patriot games: China makes its point with greatest show"by Richard Williams, ''The Guardian'', published 9 August 2008 * is also considered a lucky number in Japan, 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, 8 is the number of building, and in some theories, also the number of destruction.

In astrology

* In astrology, Scorpius, Scorpio is the 8th astrological sign of the Zodiac. * In the Middle Ages, 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 an eighth note, or quaver. * An octave, the interval between two musical notes 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, including the notes themselves and without chromatic deviation. The ecclesiastical musical mode, modes are ascending diatonic musical scales of eight notes or tones comprising an octave. * There are eight notes in the octatonic scale. * There are eight musicians in a double quartet or an octet (music), octet. Both terms may also refer to a musical composition for eight voices or instruments. * Caledonians is a square dance for eight, resembling the quadrille. * Albums with the number eight in their title include ''8'' by the Swedish band Arvingarna, ''8 (Incubus album), 8'' by the American rock band Incubus (band), Incubus, ''The Meaning of 8'' by Minnesota indie rock band Cloud Cult and ''8ight'' by Anglo-American singer-songwriter Beatie Wolfe. * Dream Theater's eighth album ''Octavarium (album), Octavarium'' 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 Unit, 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), ''8mm'' is a 1999 film directed by Joel Schumacher. * ''8 Women'' (Original French title: 8 femmes) 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 ''The Stanley Parable'' Game demo, Demonstration, there is an eight button that, when pressed, says the word eight. * In ''Mario Kart'': ** The Crazy Eight item in ''Mario Kart 8'' allows the player to use eight items at once. ** The number of characters in the starting grid in most games except for ''Mario Kart Wii'' and ''Mario Kart 8''.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. Also, an eighth of an ounce of cocaine is commonly referred to as an "8-ball." * The numeral "8" is sometimes used in informal writing and Internet slang to represent the syllable "ate", as in writing "H8" for "hate", or "congratul8ions" for "congratulations". 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)