For newer programmers, myself included, modulus is probably the most obscure operator. ie easy to understand, not always easy to find a use for. But when you see an algorithm that uses modulus, it immediately makes sense. How about a few samples where modulus works well.
For example, is a number odd or even
if(x%2 == 0)
number is even
or the old stand by for figuring out leap year
it's a leap year
what else do you guys use it for.