Bertel Lund Hansens hjemmeside

Autobiographic numbers

1210
2020
21200
3211000
42101000
521001000
6210001000

This is how far you can go with decimal numbers. A digit on the 11th position makes no sense.

If, on the other hand, you accept bases greater than 10, the following numbers are possible:

821000001000
9210000001000

and if you accept digits greater than 9, there is no limit:

A2100000001000
B21000000001000
...

Haven't you guessed the system yet? Take 1210. It has 1 zero, 2 ones, 1 two and 0 threes - 1 2 1 0.