**Congruence Class**

## Operations

**Addition**-**Subtraction**:**Multiplication**:

## Theorems

A pair of congruence classes

If gcd(a, n)

A pair of congruence classes **inverses** if and only if **invertible**“.

**Congruence Class**

**Addition**-**Subtraction**:**Multiplication**:

A pair of congruence classes

If gcd(a, n)

A pair of congruence classes **inverses** if and only if **invertible**“.