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Sexagesimal (base 60) is a numeral system with sixty as its base. It originated with the ancient Sumerians in the 3rd millennium BC, it was passed down to the ancient Babylonians, and it is still used—in a modified form—for measuring time, angles, and geographic coordinates. The number 60, a superior highly composite number, has twelve factors, namely }, of which 2, 3, and 5 are prime numbers. With so many factors, many fractions involving sexagesimal numbers are simplified. For example, one hour can be divided evenly into sections of 30 minutes, 20 minutes, 15 minutes, 12 minutes, 10 minutes, 6 minutes, 5 minutes, 4 minutes, 3 minutes, 2 minutes, and 1 minute. 60 is the smallest number that is divisible by every number from 1 to 6; that is, it is the lowest common multiple of 1, 2, 3, 4, 5, and 6. ''In this article, all sexagesimal digits are represented as decimal numbers, except where otherwise noted. (example, ''10'' means ten and ''60'' means sixty. )'' ==Origin== It is possible for people to count on their fingers to 12 using one hand only, with the thumb pointing to each finger bone on the four fingers in turn. A traditional counting system still in use in many regions of Asia works in this way, and could help to explain the occurrence of numeral systems based on 12 and 60 besides those based on 10, 20 and 5. In this system, the one (usually right) hand counts repeatedly to 12, displaying the number of iterations on the other (usually left), until five dozens, i. e. the 60, are full.〔. Translated from the French by David Bellos, E.F. Harding, Sophie Wood and Ian Monk.〕 According to Otto Neugebauer, the origins of the sixty-count was through a count of three twenties. The precursor to the later six-ten alternation was through symbols for the sixths, (i.e. 1/6, 2/6, 3/6, 4/6, 5/6), coupled with decimal numbers, led to the same three-score count, and also to the division-system that the Sumerians were famous for. In normal use, numbers were a haphazard collection of units, tens, sixties, and hundreds. A number like 192, would be expressed uniformly in the tables as 3A2 (with A as the symbol for the '10') but would in the surrounding text be given as XIxxxii i.e., hundred (big 10), sixty (big 1), three tens (little 10's), two (little 1's). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「sexagesimal」の詳細全文を読む スポンサード リンク
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