“Sixty is the base number of the Sumerian number system, fully evolved in Mesopotamia (modern-day Iraq) by 3000 BC, and it remains the essence of how we measure time: sixty seconds in a minute, sixty minutes in an hour. The number is also the base of of the 360 degrees of a circle, as in the fully imagined sky of the Sumerians (of which only a portion was visible from temple roofs), divided into six houses of 60 degrees. In Sumerian culture, the number 1 was expressed by a simple wedge, cut into clay or wood, and 60 by a great wedge.
Sixty has the versatility of being neatly divisible by 30, 20, 15, 12, 10, 6, 5, 4, 3, and 2, and therefore makes for easy subdivision of irrigated land and the harvested crops which were initially gathered in sixty-fold sheaves, just as in pre-decimal English currency sixty pennies (60d) were a crown (five shillings/5s).”
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.