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 19
base 19 is a positional numeral system with nineteen as its base. It uses 19 different digits for representing numbers. The digits for base 19 could be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, a, b, c, d, e, f, g, h, and i.