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.
hexadecimal (base 16)
The vigesimal or base 20 numeral system is based on twenty (in the same way in which the decimal numeral system is based on ten).