Find the least residue (modulo p) using Fermat's Little Theorem; or find the remainder when dividing by p. We start with a simple example, so that we can easily check the answer, then look at much bigger numbers where the answers cannot be directly checked on a calculator. 0:00 Fermat's Little Theorem: Least residue of a large number... 0:20 ...or: Remainder when dividing by a prime 0:50: Formula 1:50 Small Example 5:30 Big Example 8:40 Very Big Example