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-8 (also called octal) number system uses eight symbols to code information. Most commonly, these symbols are, 0, 1, 2, 3, 4, 5, 6 and 7.