Definition:Multiplicative Order of Integer

Context
Number Theory

Definition
Let $$a$$ and $$n$$ be integers.

Then the order of $$a$$ modulo $$n$$ is the least positive integer $$c$$ such that:
 * $$a^c \equiv 1 \left({\bmod\, n}\right)$$

if such a number $$c$$ exists.