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 23
base 23 is a positional numeral system with twenty-three as its base. It uses 23 different digits for representing numbers. The digits for base 23 could be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, a, b, c, d, e, f, g, h, i, j, k, l, and m.