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).
base 16
base 16 is a positional numeral system with sixteen as its base. It uses 16 different digits for representing numbers. The digits for base 16 could be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, a, b, c, d, e, and f.