The binary number system is a system with 2 unique symbols (0 and 1), and its base is 2.
◦ The octal number system is composed of 8 unique symbols (0, 1, 2, 3, 4, 5, 6, 7), and its base is 8.
◦ The decimal number system is composed of 10 unique symbols (0, 1, 2, 3, 4, 5, 6, 7, 8, 9), and its base (radix) is 10.
◦ The hexadecimal number system is composed of 16 symbols (0 through 9 plus the letters A, B, C, D, E, F), and its base is 16.