View source for 20 (number)

{{Infobox number
| number =  20
| numeral = [[Vigesimal|vigesimal]]
| divisor = 1, 2, 4, 5, 10, 20
}}

'''20''' ('''twenty'''; Roman numeral XX) is the [[Natural number|natural number]] following [[19 (number)|19]] and preceding [[21 (number)|21]]. A group of twenty units may also be referred to as a '''score'''.<ref>John H. Conway and Richard K. Guy, ''The Book of Numbers''. New York: Copernicus (1996): 11. ""Score" is related to "share"  and comes from the Old Norse "skor" meaning a "notch" or "tally" on a stick used for counting. ... Often people counted in 20s; every 20th notch was larger, and so "score" also came to mean 20."</ref><ref>{{Cite web|title=score {{!}} Origin and meaning of score by Online Etymology Dictionary|url=https://www.etymonline.com/word/score|access-date=2020-08-16|website=www.etymonline.com|language=en}}</ref>

== In mathematics ==
[[File:Icosahedron.svg|140px|thumb|An [[Icosahedron|icosahedron]] has twenty triangular [[Face (geometry)|faces]].]]

Twenty is a [[Pronic number|pronic number]], as it is the product of consecutive integers, namely 4 and 5.<ref>{{Cite web|url=https://oeis.org/A002378|title=Sloane's A002378: Pronic numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2020-11-30}}</ref> It is the third [[Composite number|composite number]] to be the product of a squared prime and a prime, and also the second member of the ''2''<sup>2</sup> × ''q'' family in this form.

20 has an [[Aliquot sum|aliquot sum]] of [[22 (number)|22]]; a [[Semiprime|semiprime]], within an [[Aliquot sequence|aliquot sequence]] of four composite numbers (20, 22, [[14 (number)|14]], [[10|10]], [[8|8]]) that belong to the prime [[7|7]]-aliquot tree.

*20 is the smallest [[Primitive abundant number|primitive abundant number]].<ref>{{Cite web|url=https://oeis.org/A071395|title=Sloane's A071395 : Primitive abundant numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-05-31}}</ref>
*20 is the third tetrahedral number.<ref>{{Cite web|url=https://oeis.org/A000292|title=Sloane's A000292 : Tetrahedral numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-05-31}}</ref>
*20 is the basis for [[Vigesimal|vigesimal]] number systems.<ref>{{Cite web|last=Weisstein|first=Eric W.|title=Vigesimal|url=https://mathworld.wolfram.com/Vigesimal.html|access-date=2020-08-16|website=mathworld.wolfram.com|language=en}}</ref>
*20 is the number of parallelogram polyominoes with 5 cells.<ref>{{cite OEIS|A006958|Number of parallelogram polyominoes with n cells (also called staircase polyominoes, although that term is overused)}}</ref>
*20 is the number of moves (quarter or half turns) required to optimally solve a Rubik's Cube in the worst case.<ref name="GN20">[http://www.cube20.org/ "God's Number is 20"]. Cube20.org</ref><ref>{{cite news |author=Jonathan Fildes  |work=BBC News |title=Rubik's Cube quest for speedy solution comes to an end |url=https://www.bbc.co.uk/news/technology-10929159 |date=August 11, 2010}}</ref>
*20 is the length of a [[Right triangle#Sides|side]] of the fifth smallest [[Right triangle|right triangle]] that forms a [[Pythagorean triple#Examples|primitive Pythagorean triple]], (20,21,29).<ref>{{Cite OEIS |A103606 |Primitive Pythagorean triples in nondecreasing order of perimeter, with each triple in increasing order, and if perimeters coincide then increasing order of the even members. |access-date=2023-07-06 }}</ref> This is the second Pythagorean triple <math>(a,b,c)</math> that can be formed using [[Pell number#Pythagorean triples|Pell numbers]] where <math>a</math> and <math>b</math> are [[1|one]] unit apart.{{efn|content=The first such triple is the smallest Pythagorean triple, (4,3,5). These can be formed using Pell numbers that yield a Pythagorean triple of the form {{math|1=<math>\left(2P_{n}P_{n+1}, P_{n+1}^2 - P_{n}^2, P_{n+1}^2 + P_{n}^2=P_{2n+1}\right)</math>}}. }}
*20 is the smallest non-trivial [[Decimal|decimal]] ''neon number'' equal to the sum of its digits when raised to the thirteenth power (20<sup>13</sup> = [[8192 (number)|8192]] × 10<sup>13</sup>).{{citation needed|date=September 2023}}

20 is the first number to have an ''[[Abundant number|abundance]]'' of [[2|2]], followed by [[104 (number)|104]].<ref>{{Cite OEIS |A088831 |Numbers k whose abundance is 2: sigma(k) - 2k is 2. |access-date=2024-01-23 }}</ref>

[[Gelfond's constant]] and [[Pi|pi]] ''[[Almost integer|very nearly]]'' have a difference equal to twenty:

<math display="block">e^\pi - \pi \; \approx \; 20</math>

differing only by about <math>-0.000900020811\ldots</math> from an [[Integer|integer]] value.<ref>{{Cite journal |last1=Maze |first1=Gérard |last2=Minder |first2=Lorenz |title=A new family of almost identities |url=https://ems.press/journals/em/articles/1443 |journal=[[Elemente der Mathematik]] |publisher=European Mathematical Society |location=Hensinki |year=2007 |volume=62 |number=3 |page=90 |doi=10.4171/EM/61 |mr=2350250 |zbl=1213.40002 |s2cid=56024534 |doi-access=free |arxiv=math/0409014 }}</ref><ref>{{Cite OEIS |A018938 |Decimal expansion of e^Pi - Pi. |access-date=2023-12-09 }}</ref>

There are twenty edge-to-edge [[Euclidean tilings by convex regular polygons#k-uniform tilings|2-uniform tilings]] by convex regular polygons, which are uniform tessellations of the plane containing 2 [[Group action#Orbits and stabilizers|orbits]] of [[Vertex (geometry)|vertices]].<ref>{{Cite journal |first1=Branko |last1=Grünbaum |first2=Geoffrey C. |last2=Shephard |url=https://www.maa.org/sites/default/files/images/upload_library/22/Allendoerfer/1978/0025570x.di021102.02p0230f.pdf |title=Tilings by regular polygons |journal= Mathematics Magazine |year=1977 |volume=50 |number=5 |pages=235 |doi=10.2307/2689529 |jstor=2689529 |s2cid=123776612 |zbl=0385.51006 }}</ref><ref>{{Cite OEIS |A068599 |Number of n-uniform tilings. |access-date=2023-01-07 }}</ref>

The largest number of faces a [[Platonic solid]] can have is twenty faces, which make up a regular [[Regular icosahedron|icosahedron]].<ref>{{Cite web|last=Weisstein|first=Eric W.|title=Icosahedron|url=https://mathworld.wolfram.com/Icosahedron.html|access-date=2020-08-16|website=mathworld.wolfram.com|language=en}}</ref> A [[Dodecahedron|dodecahedron]], on the other hand, has twenty vertices, likewise the most a regular polyhedron can have.<ref>{{Cite web|last=Weisstein|first=Eric W.|title=Dodecahedron|url=https://mathworld.wolfram.com/Dodecahedron.html|access-date=2020-08-16|website=mathworld.wolfram.com|language=en}}</ref> There are a total of 20 [[Regular polyhedron|regular]] and [[Semiregular polyhedron|semiregular]] polyhedra, aside from the infinite family of semiregular [[Prism (geometry)|prisms]] and antiprisms that exists in the third dimension: the 5 Platonic solids, and 15 [[Archimedean solid|Archimedean]] solids (including [[Chirality (mathematics)|chiral]] forms of the [[Snub cube|snub cube]] and [[Snub dodecahedron|snub dodecahedron]]). There are also four [[Uniform polyhedron compound|uniform compound polyhedra]] that contain twenty polyhedra ([[Compound of twenty octahedra with rotational freedom|UC<sub>13</sub>]], [[Compound of twenty octahedra|UC<sub>14</sub>]], [[Compound of twenty tetrahemihexahedra|UC<sub>19</sub>]], [[Compound of twenty triangular prisms|UC<sub>33</sub>]]), which is the most any such solids can have; while another twenty uniform compounds contain five polyhedra. The [[Compound of twenty octahedra|compound of twenty octahedra]] can be obtained by orienting two pairs of [[Compound of ten octahedra|compounds of ten octahedra]], which can also coincide to yield a regular [[Compound of five octahedra|compound of five octahedra]].

In total, there are 20 [[Semiregular polytope|semiregular polytope]]s that only exist up through the 8th dimension, which include 13 Archimedean solids and 7 [[Semiregular polytope|Gosset polytopes]] (without counting [[Chirality (mathematics)|enantiomorphs]], or semiregular prisms and antiprisms).

[[Bring's curve]] is a [[Riemann surface]] of [[Genus (mathematics)|genus]] four, whose [[Fundamental polygon|fundamental polygon]] is a regular hyperbolic twenty-sided [[Icosagon|icosagon]], with an area equal to <math>12\pi</math> by the Gauss-Bonnet theorem.<ref>{{Cite journal |last=Weber |first=Matthias |url=https://msp.org/pjm/2005/220-1/pjm-v220-n1-p09-s.pdf |title=Kepler's small stellated dodecahedron as a Riemann surface |journal=[[Pacific Journal of Mathematics]] |volume=220 |number=1 |year=2005 |page=172 |doi=10.2140/pjm.2005.220.167 |doi-access=free |mr=2195068 |s2cid=54518859 |zbl=1100.30036 }}</ref>

The [[Sporadic group#Happy Family|Happy Family]] of [[Sporadic group|sporadic group]]s is made up of '''twenty''' finite simple groups that are all [[Subquotient|subquotient]]s of the [[Monster group|friendly giant]], the largest sporadic group. The largest [[Supersingular prime (moonshine theory)|supersingular]] prime factor that divides the order of the friendly giant is [[71 (number)|71]], which is the 20th [[Sequence|indexed]] prime number. Both 71 and 20 represent [[Generalizations of Fibonacci numbers#Convolved Fibonacci sequences|self-convolved]] Fibonacci numbers, respectively the seventh and fifth members <math>j</math> in this sequence <math>F_j^{2}</math>.<ref>{{Cite OEIS |A001629 |Self-convolution of Fibonacci numbers. |access-date=2023-07-16 }}</ref><ref>{{Cite journal |last=Moree |first=Pieter |title=Convoluted Convolved Fibonacci Numbers |url=https://cs.uwaterloo.ca/journals/JIS/VOL7/Moree/moree12.pdf |journal=[[Journal of Integer Sequences]] |volume=7 |issue=2 |publisher=University of Waterloo David R. Cheriton School of Computer Science |location=Waterloo, Ont., CA |year=2004 |page=13 (Article 04.2.2) |bibcode= 2004JIntS...7...22M |arxiv=math.CO/0311205 |mr=2084694 |s2cid=14126332 |zbl=1069.11004 }}</ref>

== In science ==

*The [[Physics:Atomic number|atomic number]] of [[Chemistry:Calcium|calcium]]
*The third [[Physics:Magic number|magic number in physics]]
*The [[Organization:International Astronomical Union|International Astronomical Union]] shower number for [[Astronomy:Coma Berenicids|Coma Berenicids]]

=== Biology ===

*The number of proteinogenic [[Chemistry:Amino acid|amino acid]]s that are encoded by the standard genetic code
*In some countries, the number 20 is used as an index in measuring [[Biology:Visual acuity|visual acuity]]. 20/20 indicates normal vision at 20 feet, although it is commonly used to mean "perfect vision". (Note that this applies only to countries using the [[Imperial units|Imperial]] system. The metric equivalent is 6/6.) When someone is able to see only after an event how things turned out, that person is often said to have had "20/20 hindsight"<ref>{{Cite web|title=Definition of 20/20|url=https://www.merriam-webster.com/dictionary/20%2F20|access-date=2020-08-16|website=www.merriam-webster.com|language=en}}</ref>

== As an indefinite number ==

* A 'score' is a group of 20 (often used in combination with a [[Cardinal number|cardinal number]], e.g. ''fourscore'' to mean 80),<ref>{{Cite web|title=Definition of SCORE|url=https://www.merriam-webster.com/dictionary/score|access-date=2020-08-16|website=www.merriam-webster.com|language=en}}</ref> but also often used as an [[Indefinite and fictitious numbers|indefinite number]]<ref name="cj">"Biblical Criticism", ''The Classical Journal'' '''36''':71:83''ff'' (March 1827) [https://books.google.com/books?id=qXg_AAAAYAAJ&pg=RA1-PA83 full text]</ref> (e.g. the newspaper headline "Scores of Typhoon Survivors Flown to Manila").<ref name="scores">"CBS News", [http://www.abs-cbnnews.com/nation/metro-manila/11/14/13/scores-typhoon-survivors-flown-manila ''Scores of Typhoon Survivors Flown to Manila'']  (November 2013)</ref>

== In sports ==
{{Hatnote|For retired sports figures who wore this number, see List of retired numbers#20}}

[[File:Dartboard unlabeled.svg|thumb|A standard dartboard is laid out as 20 [[Circular sector|sectors]].]]
* Twenty20 is a form of limited overs cricket where each team plays only 20 overs.<ref>{{Cite book|last=Cleaver|first=Dylan|url=https://books.google.com/books?id=5n6uFKpbkY0C&q=Stuart+Robertson%2C+the+marketing+manager+of+the+ECB%2C+proposed+a+20+over+per+innings+game+to+county+chairmen+in+2001+and+they+voted+11%E2%80%937+in+favour+of+adopting+the+new+format&pg=PT11|title=Brendon McCullum: Inside Twenty20|date=2010-11-03|publisher=Hachette New Zealand|isbn=978-1-86971-238-9|language=en}}</ref>
* A standard dartboard is laid out as 20 [[Circular sector|sectors]].
* The Kentucky Derby currently has a maximum field of 20 horses.<ref>{{Cite book|last=Ziemba|first=William T.|url=https://books.google.com/books?id=FxM0DwAAQBAJ&q=Kentucky+Derby+currently+has+a+maximum+field+of+20+horses.&pg=PA352|title=The Adventures Of A Modern Renaissance Academic In Investing And Gambling|date=2017-08-23|publisher=World Scientific|isbn=978-981-314-853-6|pages=352|language=en|quote=It has always been for a long time a maximum of 20 horses ...}}</ref>
* In rugby union, 20 national teams currently qualify for each edition of the men's Rugby World Cup.
* In chess, 20 is the number of legal moves for each player in the starting position.<ref>{{Cite book|last=Jordan|first=Bill|url=https://books.google.com/books?id=ZQduDwAAQBAJ&q=20++legal+moves+for+each+player+in+the+starting+position+in+chess&pg=PT179|title=Opening Moves Made Easy: A new way to learn how to play Chess openings.|publisher=Bill Jordan|language=en|quote=there are 20 legal moves for White and 20 legal replies for Black}}</ref>
* In Australian rules football, most games consist of four 20-minute quarters.<ref>{{Cite book|last=Draper|first=Nick|url=https://books.google.com/books?id=s2i2BQAAQBAJ&q=Australian+rules+football,+most+games+consist+of+four+20-minute+quarters.&pg=PA404|title=Exercise Physiology: For Health and Sports Performance|date=2014-12-05|publisher=Routledge|isbn=978-1-317-90260-7|pages=404|language=en|quote=played over four 20 min quarters}}</ref>
* Under NCAA men's basketball rules, games consist of 20-minute halves.<ref>{{Cite book|last1=Harari|first1=P. J.|url=https://books.google.com/books?id=gtNDH_pR990C&q=NCAA+men's+basketball+rules,+games+consist+of+20-minute+halves&pg=PA58|title=Basketball Made Simple: A Spectator's Guide|last2=Ominsky|first2=Dave|date=2002|publisher=First Base Sports, Inc.|isbn=978-1-884309-13-7|pages=58|language=en|quote=Duration two 20-min. halves}}</ref>
* Ice hockey games are played in three 20-minute periods.<ref>{{cite web |title=International Ice Hockey Federation - Olympic Sport |url=https://www.olympic.org/international-ice-hockey-federation#:~:text=A%20regular%20game%20consists%20of,victory%20overtime%20period%20is%20played. |website=International Olympic Committee |access-date=22 January 2021 |language=en |date=9 November 2020}}</ref>
*The current Formula 1 field size is 20.
*20 was used by Tony Stewart and Joe Gibbs Racing to win the 2002 and 2005 NASCAR Cup Series championships. It is currently used by Christopher Bell.

== Age 20 ==
*In many disciplines of [[Social:Developmental psychology|developmental psychology]], adulthood starts at age 20.<ref>{{cite web |title=Adulthood {{!}} Introduction to Psychology |url=https://courses.lumenlearning.com/wmopen-psychology/chapter/reading-adulthood/#:~:text=Adulthood%20begins%20around%2020%20years,early%2C%20middle%2C%20and%20late. |website=lumenlearning.com}}</ref>
*Formerly the age of majority in Japan and in Japanese tradition.<ref>{{cite web|url=https://www.japan-experience.com/to-know/visiting-japan/age-of-majority-in-japan-changed-to-18|title=Japan's Age of Majority Changed to 18 - Living the Japon.com|website=www.japan-experience.com|access-date=19 March 2018}}</ref>
*Age 20 is the age at which Levites in the time of King David were allowed "to do the work for the service of the house of the Lord", the Temple in Jerusalem (see First Chronicles Chapter 23, verses 24 and 27). In the time of [[Biography:Ezra|Ezra]] and Nehemiah, following the Babylonian captivity, it was Levites from the age of 20 upwards who were assigned "to oversee the work of the house of the LORD" (Ezra Chapter 3, verse 8).

==Music==
{| class="wikitable sortable"
! colspan="4" |Albums
|-
!20
!Related
!Twenty
!Related
|-
|Harry Connick, Jr.<ref>{{Citation|title=20 - Harry Connick, Jr. {{!}} Songs, Reviews, Credits {{!}} AllMusic|url=https://www.allmusic.com/album/20-mw0000197963|language=en-us|access-date=2020-08-16}}</ref>
|20+ Baron Rojo<ref>{{Citation|title=20+ - Baron Rojo {{!}} Songs, Reviews, Credits {{!}} AllMusic|url=https://www.allmusic.com/album/20--mw0000502631|language=en-us|access-date=2020-08-16}}</ref>
|Bob Baldwin<ref>{{Citation|title=Twenty - Bob Baldwin {{!}} Songs, Reviews, Credits {{!}} AllMusic|url=https://www.allmusic.com/album/twenty-mw0002562550|language=en-us|access-date=2020-08-16}}</ref>
|''Twenty+'' All-4-One<ref>{{Citation|title=Twenty + - All-4-One {{!}} Songs, Reviews, Credits {{!}} AllMusic|url=https://www.allmusic.com/album/twenty--mw0002860666|language=en-us|access-date=2020-08-17}}</ref>
|-
|Orbital<ref>{{Citation|title=20 - Orbital {{!}} Songs, Reviews, Credits {{!}} AllMusic|url=https://www.allmusic.com/album/20-mw0000820901|language=en-us|access-date=2020-08-16}}</ref>
|20% Maria Bamford<ref>{{Citation|title=20 - Harry Connick, Jr. {{!}} Songs, Reviews, Credits {{!}} AllMusic|url=https://www.allmusic.com/album/20-mw0000197963|language=en-us|access-date=2020-08-16}}</ref>
|Boyz II Men<ref>{{Citation|title=Twenty - Boyz II Men {{!}} Songs, Reviews, Credits {{!}} AllMusic|url=https://www.allmusic.com/album/twenty-mw0002228446|language=en-us|access-date=2020-08-16}}</ref>
!''20 [Twenty]'' FT Island<ref>{{Citation|title=20 (Twenty) - FT Island {{!}} User Reviews {{!}} AllMusic|url=https://www.allmusic.com/album/20-twenty-mw0002383904|language=en-us|access-date=2020-08-17}}</ref>
|-
|TLC<ref>{{Citation|title=20 - TLC {{!}} Songs, Reviews, Credits {{!}} AllMusic|url=https://www.allmusic.com/album/20-mw0002582805|language=en-us|access-date=2020-08-16}}</ref>
|
|Chicane<ref>{{Citation|title=Twenty - Chicane {{!}} Songs, Reviews, Credits {{!}} AllMusic|url=https://www.allmusic.com/album/twenty-mw0002950193|language=en-us|access-date=2020-08-17}}</ref>
|
|-
|Jars of Clay<ref>{{Citation|title=20 - Jars of Clay {{!}} Songs, Reviews, Credits {{!}} AllMusic|url=https://www.allmusic.com/album/20-mw0002697748|language=en-us|access-date=2020-08-16}}</ref>
|
|Robert Cray<ref>{{Citation|title=Twenty - Robert Cray {{!}} Songs, Reviews, Credits {{!}} AllMusic|url=https://www.allmusic.com/album/twenty-mw0000655580|language=en-us|access-date=2020-08-16}}</ref>
|
|-
|Africa Unite<ref>{{Citation|title=20 - Africa Unite {{!}} Songs, Reviews, Credits {{!}} AllMusic|url=https://www.allmusic.com/album/20-mw0000770616|language=en-us|access-date=2020-08-16}}</ref>
|
|Jebediah<ref>{{Citation|title=Twenty - Jebediah {{!}} Songs, Reviews, Credits {{!}} AllMusic|url=https://www.allmusic.com/album/twenty-mw0002852415|language=en-us|access-date=2020-08-17}}</ref>
|
|-
|Kate Rusby<ref>{{Citation|title=20 - Kate Rusby {{!}} Songs, Reviews, Credits {{!}} AllMusic|url=https://www.allmusic.com/album/20-mw0002421041|language=en-us|access-date=2020-08-16}}</ref>
|
|Lynyrd Skynyrd<ref>{{Citation|title=Twenty - Lynyrd Skynyrd {{!}} Songs, Reviews, Credits {{!}} AllMusic|url=https://www.allmusic.com/album/twenty-mw0000019811|language=en-us|access-date=2020-08-16}}</ref>
|
|-
|Hyukoh<ref>{{Citation|title=20 - Hyukoh {{!}} User Reviews {{!}} AllMusic|url=https://www.allmusic.com/album/20-mw0002789091|language=en-us|access-date=2020-08-16}}</ref>
|
|Taking Back Sunday<ref>{{Citation|title=Twenty - Taking Back Sunday {{!}} Songs, Reviews, Credits {{!}} AllMusic|url=https://www.allmusic.com/album/twenty-mw0003222461|language=en-us|access-date=2020-08-16}}</ref>
|
|-
|Pastora Soler<ref>{{Citation|title=20 - Pastora Soler {{!}} Songs, Reviews, Credits {{!}} AllMusic|url=https://www.allmusic.com/album/20-mw0002806348|language=en-us|access-date=2020-08-16}}</ref>
|
|
|
|-
|The Gift<ref>{{Citation|title=20 - The Gift {{!}} Songs, Reviews, Credits {{!}} AllMusic|url=https://www.allmusic.com/album/20-mw0002904271|language=en-us|access-date=2020-08-16}}</ref>
|
|
|
|-
|Sofa Surfers<ref>{{Citation|title=20 - Sofa Surfers {{!}} Songs, Reviews, Credits {{!}} AllMusic|url=https://www.allmusic.com/album/20-mw0003108077|language=en-us|access-date=2020-08-17}}</ref>
|
|
|
|-
|Capo Plaza<ref>{{Citation|title=20 - Capo Plaza {{!}} Songs, Reviews, Credits {{!}} AllMusic|url=https://www.allmusic.com/album/20-mw0003171370|language=en-us|access-date=2020-08-17}}</ref>
|
|
|
|-
|John Dahlbäck<ref>{{Citation|title=20 - John Dahlbäck {{!}} Songs, Reviews, Credits {{!}} AllMusic|url=https://www.allmusic.com/album/20-mw0000477712|language=en-us|access-date=2020-08-17}}</ref>
|
|
|
|}
{| class="wikitable sortable"
! colspan="3" |Songs
|-
!20
!Related
!Twenty
|-
|Ebbo Kraan<ref>{{Citation|title=20 - Ebbo Kraan {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-mt0052047171|language=en-us|access-date=2020-08-17}}</ref>
|#20 - Fat Tuesday<ref>{{Citation|title=#20 - Fat Tuesday {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-mt0005944451|language=en-us|access-date=2020-08-17}}</ref>
|The Rippingtons<ref>{{Citation|title=Twenty - The Rippingtons {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/twenty-mt0014932378|language=en-us|access-date=2020-08-17}}</ref>
|-
|Seventeen<ref>{{Citation|title=20 - Seventeen {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-mt0056556768|language=en-us|access-date=2020-08-17}}</ref>
|#20 - Aphex Twin<ref>{{Citation|title=#20 - Aphex Twin {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-mt0046455451|language=en-us|access-date=2020-08-17}}</ref>
|
|-
|Janet Jackson<ref>{{Citation|title=20 - Janet Jackson {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-mt0055814541|language=en-us|access-date=2020-08-17}}</ref>
|#20 - Tony Wilson Sextet<ref>{{Citation|title=#20 - Tony Wilson Sextet {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-mt0001927539|language=en-us|access-date=2020-08-17}}</ref>
|
|-
|Gorky's Zygotic Mynci<ref>{{Citation|title=20 - Gorky's Zygotic Mynci {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-mt0004066565|language=en-us|access-date=2020-08-17}}</ref>
|#20 - David Paul Mesler<ref>{{Citation|title=# 20 - David Paul Mesler {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/-20-mt0018091631|language=en-us|access-date=2020-08-17}}</ref>
|
|-
|Covenant<ref>{{Citation|title=20 - Covenant {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-mt0007053254|language=en-us|access-date=2020-08-17}}</ref>
|$20 - Low (band)<ref>{{Citation|title=$20 - Low {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-mt0046418944|language=en-us|access-date=2020-08-17}}</ref>
|
|-
|Car 44<ref>{{Citation|title=20 - Car 44 {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-mt0006363298|language=en-us|access-date=2020-08-17}}</ref>
|$20 - Qwiksand<ref>{{Citation|title=$20 - Qwiksand {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-mt0005300993|language=en-us|access-date=2020-08-17}}</ref>
|
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|Karma to Burn<ref>{{Citation|title=20 - Karma to Burn {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-mt0041540579|language=en-us|access-date=2020-08-17}}</ref>
|$20 - Norman Palm<ref>{{Citation|title=$20 - Norman Palm {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-mt0040418082|language=en-us|access-date=2020-08-17}}</ref>
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|Ike Yard<ref>{{Citation|title=20 - Ike Yard {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-mt0000066967|language=en-us|access-date=2020-08-17}}</ref>
|20% - Furyus<ref>{{Citation|title=20% - Furyus {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-mt0020506978|language=en-us|access-date=2020-08-17}}</ref>
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|Noah Stone<ref>{{Citation|title=20 - Noah Stone {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-mt0006708807|language=en-us|access-date=2020-08-17}}</ref>
|20% - Banfi<ref>{{Citation|title=20% - Banfi {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-mt0056659907|language=en-us|access-date=2020-08-17}}</ref>
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|Alec Empire<ref>{{Citation|title=20 - Alec Empire {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-mt0001655781|language=en-us|access-date=2020-08-17}}</ref>
| -20 - Brendon Moeller<ref>{{Citation|title=-20 - Brendon Moeller {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/-20-mt0010099433|language=en-us|access-date=2020-08-17}}</ref>
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|Beans<ref>{{Citation|title=20 - Beans {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-mt0004681425|language=en-us|access-date=2020-08-17}}</ref>
|<nowiki>-20 - Mr. 76ix</nowiki><ref>{{Citation|title=-20 - Mr. 76ix {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/-20-mt0043201522|language=en-us|access-date=2020-08-17}}</ref>
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|Damián Schwartz<ref>{{Citation|title=20 - Damián Schwartz {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-mt0010128491|language=en-us|access-date=2020-08-17}}</ref>
|20 (intro) - Janet Jackson<ref>{{Citation|title=20 (Intro) - Janet Jackson {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-intro-mt0004429737|language=en-us|access-date=2020-08-17}}</ref>
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|Anarchestra<ref>{{Citation|title=20 - Anarchestra {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-mt0019781780|language=en-us|access-date=2020-08-17}}</ref>
|20 (Palbarrio) - El Barrio<ref>{{Citation|title=20 (Palbarrio) - El Barrio {{!}} Song Info {{!}} AllMusic|url=https://www.allmusic.com/song/20-palbarrio-mt0015536008|language=en-us|access-date=2020-08-17}}</ref>
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==In other fields==
* +20 is the code for international direct dial phone calls to [[Place:Egypt|Egypt]].<ref>{{Cite web|title=international phone country calling codes|url=https://www.globaltel.com/international-call-prefixes.aspx|access-date=2020-08-16|website=www.globaltel.com}}</ref>
* CB slang for a place, being short for the [[Ten-code|ten-code]] "10–20" meaning "What is your location?"<ref>{{Cite web|title=CB Slang: Ten Codes|url=https://www.cbslang.com/10-codes/|access-date=2020-08-16|website=www.cbslang.com}}</ref>
* ''20/20'' is a primetime newsmagazine program on ABC, which in turn is taken from the expression for normal eyesight (20/20 vision).
* ''020'' is the [[ISO 3166-1 numeric]] 3 digit country code for [[Religion:Andorra|Andorra]].<ref>{{Cite web|url=https://www.iso.org/obp/ui/#search|access-date=2020-08-16|title=Welcome to the Online Browsing Platform (OBP)|website=www.iso.org}}</ref>
* The UIC Country Code for {{wipe|Russia}} identifying member countries of the [[Organization:International Union of Railways|International Union of Railways]] (UIC).
* 20 is the value of the letter ''J'' when computing the [[Check digit|check digit]] in the serial number of an [[Engineering:Intermodal container|intermodal (shipping) container]], as defined by [[ISO 6346]].
* In [[Hebrew numerals]], the letter Kaph (כ) represents twenty;<ref>{{Cite web|title=Topical Bible: Kaph|url=https://biblehub.com/topical/k/kaph.htm|access-date=2020-08-17|website=biblehub.com}}</ref> see also [[Unsolved:Gematria|gematria]], the Hebrew system of [[Unsolved:Numerology|numerology]]. Similarly the Arabic letter kāf (ك) represents twenty in the [[Abjad numerals]].
* The number of questions in the game Twenty Questions.<ref>{{Cite book|last=Toone|first=Matthew|url=https://books.google.com/books?id=aDAdZoI8PhAC&q=Game+of+20+questions&pg=PT145|title=Great Games!: 175 Games and Activities for Families, Groups and Children|date=2009|publisher=Great Games Book|isbn=978-0-9798345-5-4|pages=145|language=en|quote=Much like the classic game of 20 Questions,...}}</ref>

==See also==
* List of highways numbered 20

== References ==
{{notelist}}
{{Reflist}}

== External links ==


[[Category:Integers]]

{{Sourceattribution|20 (number)}}