10 vs 12 - A coworker nicely put it to me when I asked him why US is still using 12, as 12 inches is one foot, and he told me that during the great US expansion

10 vs 12 - A coworker nicely put it to me when I asked him why US is still using 12, as 12 inches is one foot, and he told me that during the great US expansion it was much easier to deal in units of 12 - you can divide 12 by 2, 3, 4 and 6, while 10 was divisible only by 2 and 5. Now whether that was really the case I don't know, but sounds like cool theory.