- The base, or the number of digits used, in a numbering system. For example, 2 in the binary system or 10 in the decimal system. The radix also serves as the multiplier within its numbering system. In the decimal system, for instance, each single position movement to the right of a digit represents a division by 10, while a movement to the left is a multiplication by 10. This can be seen, for example, in the number 153, where the 1 is in the hundreds position, the 5 is the tens, and the 3 is the units. Also called radix number, base (8), or base number.