base 3 is a positional numeral system with three as its base. It uses 3 different digits for representing numbers. The digits for base 3 could be 0, 1, and 2.
base 12
base 12 is a positional numeral system with twelve as its base. It uses 12 different digits for representing numbers. The digits for base 12 could be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, a, and b.