base 9 is a positional numeral system with nine as its base. It uses 9 different digits for representing numbers. The digits for base 9 could be 0, 1, 2, 3, 4, 5, 6, 7, and 8.

conversion table

base 9	base 6	base 9	base 6
1	≈ 1	12	≈ 15
2	≈ 2	13	≈ 20
3	≈ 3	14	≈ 21
4	≈ 4	15	≈ 22
5	≈ 5	16	≈ 23
6	≈ 10	17	≈ 24
7	≈ 11	18	≈ 25
8	≈ 12	20	≈ 30
10	≈ 13	21	≈ 31
11	≈ 14	22	≈ 32