unitation

from The Century Dictionary.

• noun Expression in terms of units; measurement in accordance with a system of units.
• noun The operation of adding to the units of a number, written in the Arabic notation, (10—N) times the tens (where N is any number less than 10), (10—N) times the hundreds, etc., and repeating the process until a digit is obtained. This (diminished by any multiple of N which it exceeds) is the remainder after dividing the original number by N.