Base-6 (also called senary or heximal or seximal) number system uses six symbols to code information. Most commonly, these symbols are, 0, 1, 2, 3, 4 and 5.
Base-24 number system uses 24 symbols to code information. Most commonly, these symbols are, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 'A to N' (or alternatively 'a to n').