base 11 is a positional numeral system with eleven as its base. It uses 11 different digits for representing numbers. The digits for base 11 could be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, and a.
quaternary (base 4)
Quaternary is the base-4 numeral system. It uses the digits 0, 1, 2 and 3 to represent any real number.