Senary
From Academic Kids
A senary numeral system is a base-six numeral system.
All prime numbers besides 2 and 3 end in either 1 or 5.
2,3,5,11,15,21,25,31,35,45,51,101,105,111,115,125,....
All known perfect numbers besides 6 itself end in 44.
Base 6 can be counted on hands by using each hand as a digit (0 to 5). The 0 digit is represented by a fist (no fingers out).
The senary number 3333 is equal to decimal 777.
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Fractions
Six is the product of the first two prime numbers and is adjacent to the next two prime numbers. This makes many senary fractions simple.
Decimal Senary 1/2 1/2 = 0.3 1/3 1/3 = 0.2 1/4 1/4 = 0.13 1/5 1/5 = 0.1111 recurring 1/6 1/10 = 0.1 1/7 1/11 = 0.05050505 recurring 1/8 1/12 = 0.043 1/9 1/13 = 0.04 1/10 1/14 = 0.03333 recurring 1/12 1/20 = 0.03 1/14 1/22 = 0.023232323 recurring 1/15 1/23 = 0.022222222 recurring 1/16 1/24 = 0.0213 1/18 1/30 = 0.02 1/20 1/32 = 0.014444444 recurring
See also: octal, decimal, duodecimal and hexadecimal.fr:Système senaire
