was issued 87 years ago in 1776."
Twenty is a Composite Number , its proper Divisor s being 1 , 2 , 4 , 5 and 10 . It is also the sum of the first four Triangular Number s, making it a Tetrahedral Number . 20 is the smallest Abundant Number that is not a multiple of 3. It is a Harshad Number and a Self Number .
20 is the total number of digits on the human body, which makes it a possible candidate for a numeral system.
Twenty is used as a Radix for number systems. In the old UK currency system, there were twenty Shilling s in a Pound .
A Polyhedron with twenty faces is an Icosahedron .
Twenty is the first number in an early Indian Magic Square of order 3.
- The series which began on -2286 June 5 and ended on -1006 July 13 . The duration of Saros series 20 was 1280.1 years, and it contained 72 solar eclipses.
- The number of Proteinogenic Amino Acid s that are encoded by the standard genetic code.
- 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". 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".
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- In a game of Chess both players have 20 first moves from which to choose.
- Twenty Questions is a popular Party Game .
- Twenty is the Age Of Majority in Japan ese tradition. Someone who is exactly twenty years old is described as ''hatachi''.
- The "Twenty Year Curse" refers to the pattern of the President Of The United States elected every twenty years starting with 1840 to die in office. This pattern failed when Reagan survived his time in office.
- Bands with the number twenty in their name include Matchbox Twenty and 20goto10, a synthpop band whose website is www.20goto10.us.
- A 20-minute-long entertainment program shown before some films playing in United Artists movie theaters is called "The Twenty" (spelled "The 20wenty").
- A curious survival from the Celtic Languages is preserved in folklore from the north of England; this is called the "Lincolnshire Score" or the Shepherd 's Score. This is a tally that counts twenty units using this jingle. It is or was sometimes used to count Sheep .
::''Yan, tan, tethera, pethera, pimp,''
::''sethera, lethera, hovera, dovera, dick,''
::''yanadick, tanadick, tetheradick, petheradick, bumfit,''
::''yanabumfit, tanabumfit, tetherabumfit, petherabumfit, jiggit.''
:There are several other variants, but all have similar words for at least the first five units, and the principle of counting 16 to 19 by adding ones to 15, as is done in some Celtic dialects. To compare the Score with Celtic language numbers, see Numbers In Various Languages .
20 is:
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