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 20
base 20 is a positional numeral system with twenty as its base. It uses 20 different digits for representing numbers. The digits for base 20 could be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, a, b, c, d, e, f, g, h, i, and j.