Base 62 digits: 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz Base 36 digits: 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ Base 20 digits: 0123456789ABCDEFGHIJ Hexadecimal digits: 0123456789ABCDEF Decimal digits: YOU KNOW WHAT THESE ARE!!! Binary digits: 01