base 13 is a positional numeral system with thirteen as its base. It uses 13 different digits for representing numbers. The digits for base 13 could be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, a, b, and c.
ternary (base 3)
The ternary numeral system (also called base-3) has three as its base. Analogous to a bit, a ternary digit is a trit (trinary digit). One trit is equivalent to log23 (about 1.58496) bits of information.