12 inches in a foot.
the advantage of 12 is that you can easily divide it up into 2s, 3s, 4s, and 6s, which is handy for everyday usage. what's really fucked is the number of feet in a mile: 5280, which is 8 furlongs. a furlong is equivalent to 660 feet, 220 yards, 40 rods, or 10 chains, which nobody anywhere ever uses!
basing everything on 10 is good for doing hard math, but 10 can only divide cleanly into 2s and 5s.
what we really need to do is switch our entire global society over to a base-12 number system.