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xkcd #2835: Factorial Numbers
(imgs.xkcd.com)
Alt text:
So what do we do when we get to base 10? Do we use A, B, C, etc? No: Numbers larger than about 3.6 million are simply illegal.
0 = 0
1 = 1
2 = 10
3 = 11
4 = 20
5 = 21
6 = 100
101, 110, 111, 120, 121,
200, 201, 210, 211, 220, 221, 300, 301...
Amidoinitrite