is the same as saying there exists some integer such that
which means that any that satisfies the modular equivalence must be a divisor of 120, of which there are 16: .
In the cases where the modulus is smaller than the remainder 7, we can see that the equivalence still holds. For instance,
(If we’re allowing , then I see no reason we shouldn’t also allow 2, 3, 4, 5, 6.)