20 (number)
| ||||
|---|---|---|---|---|
| Cardinal | twenty | |||
| Ordinal | 20th (twentieth) | |||
| Numeral system | vigesimal | |||
| Factorization | 22 × 5 | |||
| Divisors | 1, 2, 4, 5, 10, 20 | |||
| Greek numeral | Κ´ | |||
| Roman numeral | XX | |||
| Binary | 101002 | |||
| Ternary | 2023 | |||
| Senary | 326 | |||
| Octal | 248 | |||
| Duodecimal | 1812 | |||
| Hexadecimal | 1416 | |||
Look up twenty in Wiktionary, the free dictionary.
20 (twenty; Roman numeral XX) is the natural number following 19 and preceding 21. A group of twenty units may also be referred to as a score.[1][2]
In mathematics
- 20 is a pronic number.[3]
- 20 is a tetrahedral number as 1, 4, 10, 20.[4]
- 20 is the basis for vigesimal number systems.[5]
- 20 is the third composite number to be the product of a squared prime and a prime, and also the second member of the (22)q family in this form.
- 20 is the smallest primitive abundant number.[6]
- An icosahedron has 20 faces.[7] A dodecahedron has 20 vertices.[8]
- 20 can be written as the sum of three Fibonacci numbers uniquely, i.e. 20 = 13 + 5 + 2.[9]
- 20 is the number of moves (quarter or half turns) required to optimally solve a Rubik's Cube in the worst case.[10][11]
- 20 is the number of parallelogram polyominoes with 5 cells.[12]
In science
- The atomic number of calcium.
- The third magic number in physics.
- The International Astronomical Union shower number for Coma Berenicids.
Biology
- The number of proteinogenic amino acids that are encoded by the standard genetic code.
- In some countries, the number 20 is used as an index in measuring 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 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".[13]
As an indefinite number
- A 'score' is a group of 20 (often used in combination with a cardinal number, i.e. fourscore to mean 80),[14] but also often used as an indefinite number[15] (e.g. the newspaper headline "Scores of Typhoon Survivors Flown to Manila").[16]
In sports
- Twenty20 is a form of limited overs cricket where each team plays only 20 overs.[17]
- A standard dartboard is laid out as 20 sectors.
- The Kentucky Derby currently has a maximum field of 20 horses.[18]
- 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.[19]
- In Australian rules football, most games consist of four 20-minute quarters.[20]
- Under NCAA men's basketball rules, games consist of 20-minute halves.[21]
- Ice hockey games are played in three 20-minute periods.[22]
Age 20
- In many disciplines of developmental psychology, adulthood starts at age 20.[23]
- Formerly the age of majority in Japan and in Japanese tradition.[24]
- 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 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
| Songs | ||
|---|---|---|
| 20 | Related | Twenty |
| Ebbo Kraan[48] | #20 - Fat Tuesday[49] | The Rippingtons[50] |
| Seventeen[51] | #20 - Aphex Twin[52] | |
| Janet Jackson[53] | #20 - Tony Wilson Sextet[54] | |
| Gorky's Zygotic Mynci[55] | #20 - David Paul Mesler[56] | |
| Covenant[57] | $20 - Low (band)[58] | |
| Car 44[59] | $20 - Qwiksand[60] | |
| Karma to Burn[61] | $20 - Norman Palm[62] | |
| Ike Yard[63] | 20% - Furyus[64] | |
| Noah Stone[65] | 20% - Banfi[66] | |
| Alec Empire[67] | -20 - Brendon Moeller[68] | |
| Beans[69] | -20 - Mr. 76ix[70] | |
| Damián Schwartz[71] | 20 (intro) - Janet Jackson[72] | |
| Anarchestra[73] | 20 (Palbarrio) - El Barrio[74] | |
In other fields
- +20 is the code for international direct dial phone calls to Egypt.[75]
- CB slang for a place, being short for the ten-code "10–20" meaning "What is your location?"[76]
- 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 Andorra.[77]
- The UIC Country Code for Russia identifying member countries of the International Union of Railways (UIC).
- 20 is the value of the letter J when computing the check digit in the serial number of an intermodal (shipping) container, as defined by ISO 6346.
- In Hebrew numerals, the letter Kaph (כ) represents twenty;[78] see also gematria, the Hebrew system of numerology. Similarly the Arabic letter kāf (ك) represents twenty in the Abjad numerals.
- The number of questions in the game Twenty Questions.[79]
See also
References
- ^ 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."
- ^ "score | Origin and meaning of score by Online Etymology Dictionary". www.etymonline.com. Retrieved 2020-08-16.
- ^ "Sloane's A002378: Pronic numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2020-11-30.
- ^ "Sloane's A000292 : Tetrahedral numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-31.
- ^ Weisstein, Eric W. "Vigesimal". mathworld.wolfram.com. Retrieved 2020-08-16.
- ^ "Sloane's A071395 : Primitive abundant numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-31.
- ^ Weisstein, Eric W. "Icosahedron". mathworld.wolfram.com. Retrieved 2020-08-16.
- ^ Weisstein, Eric W. "Dodecahedron". mathworld.wolfram.com. Retrieved 2020-08-16.
- ^ Dunlap, R. A. (1997). The Golden Ratio and Fibonacci Numbers. World Scientific. pp. 72–73. ISBN 978-981-238-630-4.
- ^ "God's Number is 20". Cube20.org
- ^ Jonathan Fildes (August 11, 2010). "Rubik's Cube quest for speedy solution comes to an end". BBC News.
- ^ Sloane, N. J. A. (ed.). "Sequence A006958 (Number of parallelogram polyominoes with n cells (also called staircase polyominoes, although that term is overused))". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ "Definition of 20/20". www.merriam-webster.com. Retrieved 2020-08-16.
- ^ "Definition of SCORE". www.merriam-webster.com. Retrieved 2020-08-16.
- ^ "Biblical Criticism", The Classical Journal 36:71:83ff (March 1827) full text
- ^ "CBS News", Scores of Typhoon Survivors Flown to Manila (November 2013)
- ^ Cleaver, Dylan (2010-11-03). Brendon McCullum: Inside Twenty20. Hachette New Zealand. ISBN 978-1-86971-238-9.
- ^ Ziemba, William T. (2017-08-23). The Adventures Of A Modern Renaissance Academic In Investing And Gambling. World Scientific. p. 352. ISBN 978-981-314-853-6.
It has always been for a long time a maximum of 20 horses ...
- ^ Jordan, Bill. Opening Moves Made Easy: A new way to learn how to play Chess openings. Bill Jordan.
there are 20 legal moves for White and 20 legal replies for Black
- ^ Draper, Nick (2014-12-05). Exercise Physiology: For Health and Sports Performance. Routledge. p. 404. ISBN 978-1-317-90260-7.
played over four 20 min quarters
- ^ Harari, P. J.; Ominsky, Dave (2002). Basketball Made Simple: A Spectator's Guide. First Base Sports, Inc. p. 58. ISBN 978-1-884309-13-7.
Duration two 20-min. halves
- ^ "International Ice Hockey Federation - Olympic Sport". International Olympic Committee. 9 November 2020. Retrieved 22 January 2021.
- ^ "Adulthood | Introduction to Psychology". lumenlearning.com.
- ^ "Japan's Age of Majority Changed to 18 - Living the Japon.com". www.japan-experience.com. Retrieved 19 March 2018.
- ^ 20 - Harry Connick, Jr. | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-16
- ^ 20+ - Baron Rojo | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-16
- ^ Twenty - Bob Baldwin | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-16
- ^ Twenty + - All-4-One | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-17
- ^ 20 - Orbital | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-16
- ^ 20 - Harry Connick, Jr. | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-16
- ^ Twenty - Boyz II Men | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-16
- ^ 20 (Twenty) - FT Island | User Reviews | AllMusic, retrieved 2020-08-17
- ^ 20 - TLC | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-16
- ^ Twenty - Chicane | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-17
- ^ 20 - Jars of Clay | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-16
- ^ Twenty - Robert Cray | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-16
- ^ 20 - Africa Unite | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-16
- ^ Twenty - Jebediah | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-17
- ^ 20 - Kate Rusby | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-16
- ^ Twenty - Lynyrd Skynyrd | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-16
- ^ 20 - Hyukoh | User Reviews | AllMusic, retrieved 2020-08-16
- ^ Twenty - Taking Back Sunday | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-16
- ^ 20 - Pastora Soler | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-16
- ^ 20 - The Gift | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-16
- ^ 20 - Sofa Surfers | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-17
- ^ 20 - Capo Plaza | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-17
- ^ 20 - John Dahlbäck | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-17
- ^ 20 - Ebbo Kraan | Song Info | AllMusic, retrieved 2020-08-17
- ^ #20 - Fat Tuesday | Song Info | AllMusic, retrieved 2020-08-17
- ^ Twenty - The Rippingtons | Song Info | AllMusic, retrieved 2020-08-17
- ^ 20 - Seventeen | Song Info | AllMusic, retrieved 2020-08-17
- ^ #20 - Aphex Twin | Song Info | AllMusic, retrieved 2020-08-17
- ^ 20 - Janet Jackson | Song Info | AllMusic, retrieved 2020-08-17
- ^ #20 - Tony Wilson Sextet | Song Info | AllMusic, retrieved 2020-08-17
- ^ 20 - Gorky's Zygotic Mynci | Song Info | AllMusic, retrieved 2020-08-17
- ^ # 20 - David Paul Mesler | Song Info | AllMusic, retrieved 2020-08-17
- ^ 20 - Covenant | Song Info | AllMusic, retrieved 2020-08-17
- ^ $20 - Low | Song Info | AllMusic, retrieved 2020-08-17
- ^ 20 - Car 44 | Song Info | AllMusic, retrieved 2020-08-17
- ^ $20 - Qwiksand | Song Info | AllMusic, retrieved 2020-08-17
- ^ 20 - Karma to Burn | Song Info | AllMusic, retrieved 2020-08-17
- ^ $20 - Norman Palm | Song Info | AllMusic, retrieved 2020-08-17
- ^ 20 - Ike Yard | Song Info | AllMusic, retrieved 2020-08-17
- ^ 20% - Furyus | Song Info | AllMusic, retrieved 2020-08-17
- ^ 20 - Noah Stone | Song Info | AllMusic, retrieved 2020-08-17
- ^ 20% - Banfi | Song Info | AllMusic, retrieved 2020-08-17
- ^ 20 - Alec Empire | Song Info | AllMusic, retrieved 2020-08-17
- ^ -20 - Brendon Moeller | Song Info | AllMusic, retrieved 2020-08-17
- ^ 20 - Beans | Song Info | AllMusic, retrieved 2020-08-17
- ^ -20 - Mr. 76ix | Song Info | AllMusic, retrieved 2020-08-17
- ^ 20 - Damián Schwartz | Song Info | AllMusic, retrieved 2020-08-17
- ^ 20 (Intro) - Janet Jackson | Song Info | AllMusic, retrieved 2020-08-17
- ^ 20 - Anarchestra | Song Info | AllMusic, retrieved 2020-08-17
- ^ 20 (Palbarrio) - El Barrio | Song Info | AllMusic, retrieved 2020-08-17
- ^ "international phone country calling codes". www.globaltel.com. Retrieved 2020-08-16.
- ^ "CB Slang: Ten Codes". www.cbslang.com. Retrieved 2020-08-16.
- ^ "Welcome to the Online Browsing Platform (OBP)". www.iso.org. Retrieved 2020-08-16.
- ^ "Topical Bible: Kaph". biblehub.com. Retrieved 2020-08-17.
- ^ Toone, Matthew (2009). Great Games!: 175 Games and Activities for Families, Groups and Children. Great Games Book. p. 145. ISBN 978-0-9798345-5-4.
Much like the classic game of 20 Questions,...
External links
Media related to 20 (number) at Wikimedia Commons
