The decimal system, for instance is based on the ten digits 0..9, the binary system is based on the digits 0 and 1, the hexadecimal system is based on 16 characters (0..9 and A..F).
Десятичная система, например, базируется на числах (0..9), двоичная система – на числах 0 и 1, шестнадцатеричная – на 16 символах (0...9 и A...F).