Base-20 (also known as vigesimal) number system uses 20 symbols to code information. Most commonly, these symbols are, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 'A to J' (or alternatively 'a to j').
Base-5 (also called quinary) number system uses five symbols to code information. Most commonly, these symbols are, 0, 1, 2, 3 and 4.