Radix

A number's radix or number's base describes when the next higher digit gets incremented.

For example, in the decimal number system (base-10), incrementing beyond 9 adds an extra digit 10.
In the binary number system (base-2), incrementing beyond 01 increments the higher digit 10.

Documentation

wikipedia

https://en.wikipedia.org/wiki/Radix

Number Bases

binary:       2
octal:        8
decimal:     10
hexadecimal: 16