in ancient times, the sumerians calculated numbers in wedge shape or cuneifนพm' format. this grid comprised of 'cuneiform' format. this grid comprised of 60-number system in five groups of 12. each individual group of 12 was known as one dozen. by the way , did you know a baker's dozen' is 13--that's because the generous baker would always give an extra bread roll when his customer ordered a dozen...god for business.