View source for 8

{{Short description|Natural number}}
{{Hatnote|This article is about the number. For the years, see [[8 BC]] and [[AD 8]]. For other uses, see [[8 (disambiguation)]] and [[Number Eight (disambiguation)]].}}
{{redirect|VIII}}
{{Use dmy dates|date=October 2020}}
{{Infobox number
|number=8
|numeral=[[octal]]
|divisor=1, 2, 4, 8
|roman=VIII, viii
|greek prefix=[[Wikt:octa-|octa-]]/[[Wikt:oct-|oct-]]
|latin prefix=[[Wikt:octo-|octo-]]/[[Wikt:oct-|oct-]]
|lang1=[[Greek numerals|Greek]]
|lang1 symbol=η (or Η)
|lang2=[[Eastern Arabic numerals|Arabic]], [[Central Kurdish|Kurdish]], [[Persian language|Persian]], [[Sindhi language|Sindhi]], [[Urdu numerals|Urdu]]
|lang2 symbol={{resize|150%|٨}}
|lang3=[[Amharic]]
|lang3 symbol=፰
|lang4=[[Bengali language|Bengali]]
|lang4 symbol={{resize|150%|৮}}
|lang5=[[Chinese numeral]]
|lang5 symbol=八,捌
|lang6=[[Devanāgarī]]
|lang6 symbol={{resize|150%|८}}
|lang7=[[Santali language|Santali]]
|lang7 symbol={{resize|150%|᱘}}
|lang8=[[Kannada]]
|lang8 symbol={{resize|150%|೮}}
|lang9=[[Malayalam]]
|lang9 symbol={{resize|150%|൮}}
|lang10=[[Telugu language|Telugu]]
|lang10 symbol={{resize|150%|౮}}
|lang11=[[Tamil language|Tamil]]
|lang11 symbol={{resize|150%|௮}}
|lang12=[[Biblical Hebrew|Hebrew]]
|lang12 symbol={{resize|150%|ח}}
|lang13=[[Khmer numerals|Khmer]]
|lang13 symbol=៨
|lang14=[[Thai numerals|Thai]]
|lang14 symbol=๘
|lang15=[[Armenian language|Armenian]]
|lang15 symbol=Ը ը|lang16=[[Babylonian cuneiform numerals|Babylonian numeral]]|lang16 symbol=𒐜|lang17=[[Egyptian numerals|Egyptian hieroglyph]]|lang17 symbol={{resize|150%|𓐁}}|lang19=[[Morse code]]|lang19 symbol={{resize|150%|_ _ _..}}|cardinal=eight}}

'''8''' ('''eight''') is the [[natural number]] following [[7]] and preceding [[9]].

== Etymology ==
English ''eight'', from [[Old English]] {{Lang|ang|eahta}}'', æhta'', [[Proto-Germanic]] ''*ahto'' is a direct continuation of the [[Proto-Indo-European_language#Development_of_the_hypothesis|hypothesized]] [[Proto-Indo-European numerals|Proto-Indo-European]] ''[[:wikt:Appendix:Proto-Indo-European/oḱtṓw|*oḱtṓ(w)]]-'', and as such cognate with Greek {{lang|grc|ὀκτώ}} and Latin {{Lang|la|octo-}}, both of which stems are reflected by the English prefix [[:wikt:oct-|oct(o)-]], as in the ordinal adjective ''octaval'' or ''octavary'', the distributive adjective is ''[[octonary]]''.
The adjective ''octuple'' (Latin {{Lang|la|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.
<!--possibly but not certainly related to Egyptioan ''χmn-''-->
The [[Chinese numeral]], written {{lang|zh|八}} ([[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]]''.
<!--https://books.google.ch/books?id=nIvqAC7FNBQC&q=eight#v=onepage&q&f=false-->

It has been argued that, as the [[cardinal number]] {{num|7}} is the highest number of items 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");<ref>''Etymological Dictionary of Turkic Languages: Common Turkic and Interturkic stems starting with letters «L», «M», «N», «P», «S»'', Vostochnaja Literatura RAS, 2003, 241f. ([http://altaica.ru/LIBRARY/e_edtl.htm altaica.ru] {{Webarchive|url=https://web.archive.org/web/20071031074630/http://altaica.ru/LIBRARY/e_edtl.htm |date=31 October 2007 }})</ref>
this same principle is found in [[Uralic languages|Uralic]] ''[[:wikt:Reconstruction:Proto-Uralic/kakteksa|*kakteksa]]'', which conveys a meaning of "two before (ten)". The Proto-Indo-European reconstruction ''[[:wikt:Appendix:Proto-Indo-European/oḱtṓw|*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 ''{{num|9}}'', which might be built on the stem ''new-'', meaning "new" (indicating the beginning of a "new set of numerals" after having counted to eight).<ref>the hypothesis is discussed critically (and rejected as "without sufficient support") by
[[Werner Winter (linguist)|Werner Winter]], 'Some thought about Indo-European numerals' in: Jadranka Gvozdanović (ed.),
''Indo-European Numerals'', [[Walter de Gruyter]], 1992, 14f.</ref>

== Evolution of the Arabic digit ==

{{More citations needed section|date=May 2024}}

[[File:Evo8glyph.svg|thumb|Evolution of the numeral 8 from the [[Brahmi numerals]] to the [[Arabic numerals]]]]
The modern digit 8, like all modern [[Arabic numerals]] other than zero, originates with the [[Brahmi numerals]].
The [[Brahmi script|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.{{year needed|date=October 2014}}

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.<ref>Georges Ifrah, ''The Universal History of Numbers: From Prehistory to the Invention of the Computer'' transl. David Bellos et al. London: The Harvill Press (1998): 395, Fig. 24.68.</ref>

Just as in most modern [[typeface]]s, in typefaces with [[text figures]] the character for the digit 8 usually has an [[ascender (typography)|ascender]], as, for example, in [[File:TextFigs148.svg]].

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 mathematics ==
8 is a [[composite number]] and the first number which is neither [[Prime number|prime]] nor [[semiprime]]. By [[Catalan conjecture|Mihăilescu's Theorem]], it is the only nonzero [[perfect power]] that is one less than another perfect power. 8 is the first proper [[Leyland number]] of the form {{math|x<sup>y</sup> + y<sup>x</sup>}}, where in its case {{math|x}} and {{math|y}} both equal 2.<ref>{{Cite OEIS |A076980 |Leyland numbers }}</ref> 8 is a [[Fibonacci number]] and the only nontrivial Fibonacci number that is a [[perfect cube]].<ref>Bryan Bunch, ''The Kingdom of Infinite Number''. New York: W. H. Freeman & Company (2000): 88</ref> [[Sphenic number]]s always have exactly eight divisors.<ref>{{Cite web |last=Weisstein |first=Eric W. |title=Sphenic Number |url=https://mathworld.wolfram.com/SphenicNumber.html |access-date=2020-08-07 |website=mathworld.wolfram.com |language=en |quote=...then every sphenic number n=pqr has precisely eight positive divisors}}</ref> 8 is the base of the [[octal]] number system.<ref>{{Cite web |last=Weisstein |first=Eric W. |title=Octal |url=https://mathworld.wolfram.com/Octal.html |access-date=2020-08-07 |website=mathworld.wolfram.com |language=en}}</ref>

=== Geometry ===

A [[polygon]] with eight sides is an [[octagon]].<ref>{{Cite web |last=Weisstein |first=Eric W. |title=Octagon |url=https://mathworld.wolfram.com/Octagon.html |access-date=2020-08-07 |website=mathworld.wolfram.com |language=en}}</ref> A regular octagon can fill a [[Euclidean tilings by convex regular polygons#Plane-vertex tilings|plane-vertex]] with a regular [[triangle]] and a regular [[icositetragon]], as well as [[tessellation|tessellate]] two-dimensional space alongside squares in the [[truncated square tiling]]. This tiling is one of eight [[Archimedean tiling]]s that are semi-regular, or made of more than one type of regular [[polygon]], and the only tiling that can admit a regular octagon.<ref>{{Cite web|last=Weisstein|first=Eric W.|title=Regular Octagon |url=https://mathworld.wolfram.com/RegularOctagon.html|access-date=2022-06-25|website=mathworld.wolfram.com|language=en}}</ref>  The [[Ammann–Beenker tiling]] is a nonperiodic tesselation of [[prototile]]s that feature prominent octagonal ''silver'' eightfold symmetry, that is the two-dimensional [[orthographic projection]] of the four-dimensional [[8-8 duoprism]].<ref>{{Cite book |author =Katz, A |chapter=Matching rules and quasiperiodicity: the octagonal tilings |title=Beyond quasicrystals |publisher=Springer |year=1995 |pages=141–189 |isbn=978-3-540-59251-8 |doi=10.1007/978-3-662-03130-8_6 |editor1-first=F. |editor1-last=Axel |editor2-first=D. |editor2-last=Gratias}}</ref>

An [[octahedron]] is a [[regular polyhedron]] with eight [[equilateral triangle]]s as [[face (geometry)|faces]]. is the [[dual polyhedron]] to the cube and one of eight [[Deltahedron|convex deltahedra]].<ref>{{Citation|last1=Freudenthal|first1=H|last2=van der Waerden|first2=B. L.|authorlink1=Hans Freudenthal | authorlink2=B. L. van der Waerden|title=Over een bewering van Euclides ("On an Assertion of Euclid")|journal=[[Simon Stevin (journal)|Simon Stevin]]|volume=25|pages=115–128|year=1947|language=Dutch}}</ref><ref>{{Cite web|url=http://www.interocitors.com/polyhedra/Deltahedra/Convex |author=Roger Kaufman |title=The Convex Deltahedra And the Allowance of Coplanar Faces |website=The Kaufman Website |access-date=2022-06-25}}</ref> The [[stella octangula]], or ''eight-pointed star'', is the only [[stellation]] with [[octahedral symmetry]]. It has eight triangular faces alongside eight vertices that forms a cubic [[faceting]], composed of two self-dual [[Regular tetrahedron|tetrahedra]] that makes it the simplest of five [[Uniform polyhedron compound|regular compound]]s. The [[cuboctahedron]], on the other hand, is a [[rectification (geometry)|rectified]] cube or rectified octahedron, and one of only two convex [[Quasiregular polyhedron|quasiregular polyhedra]]. It contains eight equilateral triangular faces, whose first [[stellation]] is the [[compound of cube and octahedron|cube-octahedron compound]].<ref>{{Cite web |last=Weisstein |first=Eric W. |title=Cuboctahedron |url=https://mathworld.wolfram.com/Cuboctahedron.html |access-date=2022-06-25 |website=mathworld.wolfram.com |language=en }}</ref><ref>{{Cite book |last=Coxeter |first=H.S.M. |author-link=Harold Scott MacDonald Coxeter |year=1973 |orig-year=1948 |title=Regular Polytopes |publisher=Dover |place=New York |edition=3rd |pages=18–19 |title-link=Regular Polytopes (book) }}</ref>

=== Vector spaces===

The [[octonion]]s are a [[Hypercomplex numbers|hypercomplex]] [[normed division algebra]] that are an extension of the [[complex number]]s. They are a [[Double covering group|double cover]] of [[special orthogonal group]] SO(8). The [[special unitary group]] SO(3) has an eight-dimensional [[adjoint representation]] whose colors are ascribed [[Gauge symmetry (mathematics)|gauge symmetries]] that represent the [[Vector (mathematics)|vectors]] of the eight [[gluon]]s in the [[Standard Model]]. [[Clifford algebra]]s display a periodicity of 8.<ref>{{Cite book|last=Lounesto|first=Pertti|url=https://books.google.com/books?id=DTecU6UpkSgC&q=Clifford+algebras+also+display+a+periodicity+of+8.&pg=PA216|title=Clifford Algebras and Spinors|date=2001-05-03|publisher=Cambridge University Press |isbn=978-0-521-00551-7|pages=216|language=en|quote=...Clifford algebras, contains or continues with two kinds of periodicities of 8...}}</ref>

=== Group theory ===

The [[Group of Lie type|Lie group]] [[E8 (mathematics)|'''E<sub>8</sub>''']] has [[Rank of a group|rank]] 8, and is one of 5 exceptional Lie groups.<ref>{{Cite journal |last1=Wilson |first1=Robert A. |author-link=Robert Arnott Wilson |title=Octonions and the Leech lattice |mr=2542837 |year=2009 |journal=Journal of Algebra |volume=322 |issue=6 |pages=2186–2190|doi=10.1016/j.jalgebra.2009.03.021 |doi-access=free }}</ref><ref>{{Cite book |last1=Conway |first1=John H. |author1-link=John Horton Conway |last2=Sloane |first2=N. J. A. |author2-link=Neil Sloane |chapter-url=https://link.springer.com/chapter/10.1007/978-1-4757-2016-7_8  |title=Sphere Packings, Lattices and Groups |title-link=Sphere Packings, Lattices and Groups |chapter=Algebraic Constructions for Lattices |publisher=Springer |location=New York, NY |year=1988 |isbn=978-1-4757-2016-7 |eissn=2196-9701  |doi=10.1007/978-1-4757-2016-7 }}</ref> The order of the smallest [[non-abelian group]] whose subgroups are all normal is 8.{{Citation needed|date=October 2024}}

=== List of basic calculations ===
{|class="wikitable" style="text-align: center; background: white"
|-
! style="width:105px;"|[[Multiplication]]
!1
!2
!3
!4
!5
!6
!7
!8
!9
!10
!11
!12
!13
!14
!15
|-
|'''8 × ''x'''''
|'''8'''
|[[16 (number)|16]]
|[[24 (number)|24]]
|[[32 (number)|32]]
|[[40 (number)|40]]
|[[48 (number)|48]]
|[[56 (number)|56]]
|[[64 (number)|64]]
|[[72 (number)|72]]
|[[80 (number)|80]]
|[[88 (number)|88]]
|[[96 (number)|96]]
|[[104 (number)|104]]
|[[112 (number)|112]]
|[[120 (number)|120]]
|}

{|class="wikitable" style="text-align: center; background: white"
|-
! style="width:105px;"|[[Division (mathematics)|Division]]
!1
!2
!3
!4
!5
!6
!7
!8
!9
!10
! style="width:5px;"|
!11
!12
!13
!14
!15
|-
|'''8 ÷ ''x'''''
|'''8'''
|4
|2.{{overline|6}}
|2
|1.6
|1.{{overline|3}}
|1.{{overline|142857}}
|1
|0.{{overline|8}}
|0.8
!
|0.{{overline|72}}
|0.{{overline|6}}
|0.{{overline|615384}}
|0.{{overline|571428}}
|0.5{{overline|3}}
|-
|'''''x'' ÷ 8'''
|0.125
|0.25
|0.375
|0.5
|0.625
|0.75
|0.875
|1
|1.125
|1.25
!
|1.375
|1.5
|1.625
|1.75
|1.875
|}

{|class="wikitable" style="text-align: center; background: white"
|-
! style="width:105px;"|[[Exponentiation]]
!1
!2
!3
!4
!5
!6
!7
!8
!9
!10
! style="width:5px;"|
!11
!12
!13
|-
|'''8{{sup|''x''}}'''
|'''8'''
|64
|512
|4096
|32768
|262144
|2097152
|16777216
|134217728
|1073741824
!
|8589934592
|68719476736
|549755813888
|-
|'''''x''{{sup|8}}'''
|1
|256
|6561
|65536
|390625
|1679616
|5764801
|16777216
|43046721
|100000000
!
|214358881
|429981696
|815730721
|}

== In science ==
=== Physics ===
In nuclear physics, the second [[Magic number (physics)|magic number]].<ref>{{Cite book |last=Ilangovan |first=K. |url=https://books.google.com/books?id=E4GcDwAAQBAJ&q=8+magic+number+nuclear+physics&pg=PA31 |title=Nuclear Physics |date=2019-06-10 |publisher=MJP Publisher |pages=30 |language=en}}</ref>

=== Chemistry ===
The number eight plays a central role in [[chemistry]], particularly in the context of the [[octet rule]] (also known as the eight-electron rule). According to this theory, atoms of the main group elements from the second period of the [[periodic table]] onwards strive to have a maximum of eight outer electrons ([[valence electron]]s) in [[molecule]]s in order to achieve a stable [[noble gas]] configuration. This rule applies in particular to the elements [[carbon]], [[nitrogen]], [[oxygen]] and [[fluorine]], as these often form compounds in which they achieve eight valence electrons. The [[atomic number]] eight is also significant in chemistry, as it represents the element oxygen, which is in the eighth position in the periodic table.

== In technology ==
[[File:ICS Eight.svg|right|thumb|100px|[[Naval flag signalling#Numerals|NATO signal flag]] for 8]]
* A [[byte]] is eight [[bit]]s.<ref>{{Cite web|title=Definition of byte {{!}} Dictionary.com|url=https://www.dictionary.com/browse/byte|access-date=2020-08-08|website=www.dictionary.com|language=en}}</ref>

== In culture ==

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

=== In religion, folk belief and divination ===

==== Buddhism ====
[[File:Dharma Wheel.svg|thumb|right|In Buddhism, the 8-spoked [[Dharmacakra]] represents the [[Noble Eightfold Path]].]]
In general, "eight" seems to be an auspicious number for Buddhists. The [[Dharmacakra]], a [[Buddhism|Buddhist]] symbol, has eight spokes.<ref>{{Cite book|last1=Issitt|first1=Micah|url=https://books.google.com/books?id=kmFhBQAAQBAJ&q=Dharmacakra,+a+Buddhist+symbol,+has+eight+spokes.&pg=PA186|title=Hidden Religion: The Greatest Mysteries and Symbols of the World's Religious Beliefs: The Greatest Mysteries and Symbols of the World's Religious Beliefs|last2=Main|first2=Carlyn|date=2014-09-16|publisher=ABC-CLIO|isbn=978-1-61069-478-0|pages=186|language=en|quote=The dharmachakra is typically depicted with eight spokes,}}</ref> 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.

==== Islam ====
[[File:Rub_El_Hizb.svg|thumb|right|110px|The [[octagram]] ''[[Rub el Hizb]]'']]
* The [[octagram]] ''[[Rub el Hizb]]'' is often used in Islamic symbology.

====As a lucky number====<!--This section is linked from [[2008 Summer Olympics]]-->
* The number eight is considered to be a [[Numbers in Chinese culture|lucky number in Chinese]] and other Asian cultures.<ref>{{Cite journal |last=Ang |first=Swee Hoon |title=Chinese consumers' perception of alpha-numeric brand names |journal=Journal of Consumer Marketing |year=1997 |volume=14 |issue=3 |pages=220–233 |url=http://www.emeraldinsight.com/journals.htm?articleid=856257&show=abstract |doi=10.1108/07363769710166800 |archive-url=https://web.archive.org/web/20111205013132/http://www.emeraldinsight.com/journals.htm?articleid=856257&show=abstract |archive-date=5 December 2011 |url-status=live |df=dmy-all }}</ref> Eight ({{lang|zh-Hani|八}}; [[Chinese numerals#Numeral characters|accounting]] {{lang|zh-Hani|捌}}; [[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 ({{lang|zh-Hant|發(T) 发(S)}}; [[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.<ref>{{Cite journal |url=http://www.umac.edu.mo/fba/irer/papers/past/vol2_pdf/079-093LN-NZ.pdf |journal=International Real Estate Review |year=1999 |volume=2 |pages=79–93 |title=Hedonic Prices and House Numbers: The Influence of Feng Shui |author1=Steven C. Bourassa |author2=Vincent S. Peng |issue=1 |url-status=dead |archive-url=https://www.webcitation.org/6XlGD7PlK?url=http://www.umac.edu.mo/fba/irer/papers/past/vol2_pdf/079-093LN-NZ.pdf |archive-date=13 April 2015 |df=dmy-all |access-date=11 May 2011 }}</ref> The opening ceremony of the [[2008 Summer Olympics|Summer Olympics in Beijing]] started at 8 seconds and 8 minutes past 8 p.m. (local time) on 8 August 2008.<ref name="game">{{Cite web |date=2008-08-08|title=Olympics opening ceremony: China makes its point with greatestshow|url=http://www.theguardian.com/sport/2008/aug/09/olympics2008.openingceremony|access-date=2022-11-29|website=the Guardian|language=en}}</ref>
* In Pythagorean [[numerology]] the number 8 represents victory, prosperity and overcoming.
* {{Nihongo|Eight|八|hachi, ya}} is also considered a lucky number in [[Japan]], but the reason is different from that in Chinese culture.<ref>{{Cite book|last=Jefkins|first=Frank|url=https://books.google.com/books?id=sbWvBQAAQBAJ&q=Eight++is+also+considered+a+lucky+number+in+Japan&pg=PA36|title=Modern Marketing Communications|date=2012-12-06|publisher=Springer Science & Business Media|isbn=978-94-011-6868-7|pages=36|language=en|quote=...eight being a lucky number in Japanese.}}</ref> Eight gives an idea of growing prosperous, because the letter ({{nihongo2|八}}) broadens gradually.
* The Japanese thought of {{Nihongo|eight|や|ya}} 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 {{Nihongo|manyfold|やえはたえ|Yae Hatae}} (literally, eightfold and twentyfold), {{Nihongo|many clouds|やくも|Yakumo}} (literally, eight clouds), {{Nihongo|millions and millions of Gods|やおよろずのかみ|Yaoyorozu no Kami}} (literally, eight millions of Gods), etc. It is also guessed that the ancient Japanese gave importance to pairs, so some researchers guess twice as {{Nihongo|four|よ|yo}}, 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 the [[Middle Ages]], 8 was the number of "unmoving" stars in the sky, and symbolized the perfection of incoming planetary energy.

=== In sports and other games ===
[[File:8-Ball.jpg|thumb|An 8-ball in pool]]
* In [[association football]], the number 8 has historically been the number of the Central Midfielder.
* In [[baseball]]:
** The [[center fielder]] is designated as number 8 for scorekeeping purposes.
* 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.
* 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&nbsp;p.m. [[China Standard Time|CST]].

=== In literature ===
* In [[Terry Pratchett]]'s ''[[Discworld]]'' series, eight is a magical number<ref>{{Cite book |last1=Collins |first1=Robert |url=https://books.google.com/books?id=LskbAQAAIAAJ&q=Terry+Pratchett's+Discworld+series,+eight+is+a+magical+number |title=Science Fiction & Fantasy Book Review Annual |last2=Latham |first2=Robert |date=1988 |publisher=Meckler |pages=289 |isbn=978-0-88736-249-1 |language=en}}</ref> 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]].

=== 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]].<ref>{{Cite web |last=Franciosi |first=Anthony |date=2019-10-25 |title=Weed Measurements: The Marijuana Metric System |url=https://honestmarijuana.com/weed-measurements/ |access-date=2023-12-19 |website=Honest Marijuana |language=en-US}}</ref>
* 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".

===Other uses===
* A figure 8 is the common name of a [[geometry|geometric]] [[shape]], often used in the context of sports, such as skating.<ref>{{Cite book |url=https://books.google.com/books?id=9v0Me0lNg48C&q=figure+8+skating.&pg=PA20 |title=Boys' Life |date=1931 |publisher=Boy Scouts of America, Inc. |pages=20 |language=en |quote=lunge forward upon this skate in a left outside forward circle, in just the reverse of your right outside forward circle, until you complete a figure 8.}}</ref> Figure-eight turns of a rope or cable around a cleat, pin, or bitt are used to belay something.<ref>{{Cite book|last=Day|first=Cyrus Lawrence |url=https://books.google.com/books?id=-F0sAAAAYAAJ&q=Figure-eight+turns+of+a+rope+or+cable+around+a+cleat,+pin,+or+bitt+are+used+to+belay+something |title=The Art of Knotting & Splicing |date=1986 |publisher=Naval Institute Press|isbn=978-0-87021-062-4|pages=231|language=en|quote=To make a line temporarily fast by winding it, figure – eight fashion, round a cleat, a belaying pin, or a pair of bitts.}}</ref>

== References ==
{{Reflist}}

== External links ==
* [https://web.archive.org/web/20090421054044/http://math.ucr.edu/home/baez/octonions/octonions.html The Octonions], John C. Baez

{{Integers|zero}}
{{Authority control}}

{{DEFAULTSORT:8 (Number)}}
[[Category:Integers]]
[[Category:8 (number)]]