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.
duodecimal (base 12)
The duodecimal system (also known as base 12 or dozenal) is a positional notation numeral system using twelve as its base.