This is something I’ve always wondered. The answer may surprise you.
It
is easy to see the origins of a decimal (base 10) number system. Our
hands have 10 digits to count on, so a decimal system follows naturally.
With the addition of the toes on
our feet a vigesimal (base 20) number system, like that of the Maya,
also makes sense. But understanding a sexagesimal (base 60) number
system, as used by the Sumerians, takes a little more thought.A quick glance at a hand shows us four fingers and a thumb that can
be used for counting. But the human hand is a complex machine consisting
of 27 bones.
Read more here.