Recognizing when to use the modulus operator

Question

I know the modulus (%) operator calculates the remainder of a division. How can I identify a situation where I would need to use the modulus operator?

I know I can u

Answer 1

My favorite use is for iteration.

Say you have a counter you are incrementing and want to then grab from a known list a corresponding items, but you only have n items to choose from and you want to repeat a cycle.

var indexFromB = (counter-1)%n+1;

Results (counter=indexFromB) given n=3:

`1=1`
`2=2`
`3=3`
`4=1`
`5=2`
`6=3`
...