“The circle is divided into 360 degrees, which is an attempt to create a perfect universe out of our slightly wonky one. For 360 can be neatly divided by 4 to make 90-day seasons, or by 12 to make perfect months of 30 days, or by 18 to make 20-day units. This perfect ordering of the world—the sexagesimal system—was codified by the Babylonians and still orders the world of geometry and time-keeping with 60 seconds in a minute and sixty minutes in an hour.
Of course, the reality of our world was never quite as neat as those Babylonian mathematicians aspired to be, for a lunar month is actually 29 days 12 hours, and 44 minutes, not a neat 30, and a solar year (the time in which it takes the earth to orbit the sun) is actually 365 days, five hours, and 48 minutes, not a neat 360. So, in the old days, we made an odd thirteenth month of five days, before opting to spread them around to make some months 30 days long, some 31. And every fourth year we need our years to be 366 days long, in order to use up an extra day acquired by four additional units of five hours and 48 minutes.
Nonetheless, the perfection of 360 has always been aspired to, with ancient stone circles formed of 360 stones and altars formed from 360 cut stones.”
Excerpted from: Rogerson, Barnaby. Rogerson’s Book of Numbers: The Culture of Numbers–from 1,001 Nights to the Seven Wonders of the World. New York: Picador, 2013.