base 12 is a positional numeral system with twelve as its base. It uses 12 different digits for representing numbers. The digits for base 12 could be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, a, and b.
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).