How useful is the modulo operator?

Question

Could someone explain to me what the modulo could help in terms of making a program and also some examples?

Answer 1

the modulo can help in limiting a number to a certain range that you don't mind wrapping around (coordinates for example)

the modulo can help you find out if a number is even or odd

the modulo can be used in encryption (Diffie-Hellman Key Exchange is based on it)

i am sure it's used for lots more!

Answer 2

it is also useful for performing operations in loops. for example, index % 2 == 0 would allow you to work on every even number. index % 3 == 0 could be used for every third number ec... Also since integers truncate, it is useful for determining if a value is divisible by another. 8 / 8 is 1 as is 13 / 8 whereras 8 % 8 == 0 so you know that a value is divisible IF it equals 0 after modulo.