Kinda weird now that you bring it up. We use 13 and say 1, 14 we call 2, 15 is 3, 16 is 4, 17 is 5, 18 is 6, 19 is 7, 20 is 8, 21 is 9, 22 is 10, 23 is 11 and last but not least 0 means 12.

It seems like a bad idea if I've ever seen 13.