# The number 12

Why is the number 12 remarkable? This is the number of months in a year the number of units in a dozen. But what is special in the number 12? Few realize that the number 12 - the old and nearly winning the number 10 contender in the fight for the honorary post of radix. The civilized peoples of the ancient East – the babylonians and their predecessors who inhabit Mesopotamia, scored in duodecimal. And if not overpower the influence of India, gave us the decimal system, we probably would have inherited from Babylon, 12-ary system.

How well do that in the struggle between 12 and 10 won the last digit? Of course, powerful allies of dozens were and remain our own hands with ten fingers. But, if not for this, we would definitely prefer 12 to 10. It is much more convenient to make payments on a 12-ary system, rather than decimal. The reason is that the number of 10 is divisible by 2 and 5, while 12 divided by 2, 3, 4, and 6. 10 has 2 divider, 12 - four. The 12-hexadecimal number system, ending with a zero, a multiple of 2, 3, 4 and 6; how convenient to split up the numbers when 1/2, 1/3, 1/4 and 1/6 must be integers.

If the number in a 12-ary system ends in two zeros, then it must be evenly divisible by 144, and, consequently, all the multipliers 144 (2, 3, 4, 6, 8, 9, 12, 16, 18, 24, 36, 48, 72, 144). Fourteen subgroups - instead of the eight that are in the decimal number system (2, 4, 5, 10, 20, 25, 50, 100).

The number 12 has some interesting properties. This perimeter classical Egyptian or Pythagorean triangle with sides 3: 4: 5. In three-dimensional Euclidean space can be placed up to 12 non-overlapping spheres of unit radius, concerning sphere of unit radius. Humans have 12 pairs of ribs; 12 pairs of cranial nerves in mammals.

Pick up any wall calendar. Consider any month. If you multiply all the numbers in any vertical column, the resulting number is necessarily divisible by 12.