Is it a stupid idea to have another word for twelve?
The Romans. There was 12 ounces in a Roman pound and 12 pounds in a Roman stone. A carat of diamond is 1/144 Roman ounces. There was 12 lines in an inch and 12 inches in a foot. I could go on if you like. The old myth that you can't multiply in Roman numerals disappears if you know to work in 12s instead of 10s like you were taught.
I thought the problem with multiplying in Roman numerals was their lack of positional notation?
The Sumerians had a weird system that could have been base 10 if they had wanted. They got to 59 by writting 5 ten symbols and 9 one symbols, but instead of writing 6 ten symbol, they put 1 one symbol in the next position. 60 has the nontrivial factors, 2, 3, 4, 5, 6, 10, 12, 15, 20 and 30, where as 10 only has 2 and 5. My guess that it is because 60 is divisble by 1,2,3,4,5 and 6, they liked it for dividing circles.
You can learn a lot from circles, for example you can use a sequence of circles to construct an approximation of the squareroot of 2.
one, "a", only; two, pair, twin, double; three, tripplet, trine; four ummm... ok, i can't think of any for 4, 5, 6, 7, or 8 that are actually used.
Now, riddle me this: why did baker's dozen come about?