The number base of a number system defines how many digits are in the number system, and the base of the exponent for each place value in a number.
For example, in the base 10 number system (decimal), we can use 10 different digits (0 - 9). The place value of each position in a number is determined by 10 raised to the place’s index:
2 3 4
10^2 10^1 10^0
100s 10s 1s