One arithmetic operator that we haven’t covered yet and may be less familiar is a modulo. A modulo returns a remainder, what is left over when we divide a number by another number.

4 % 3 = 1 4 % 2 = 0

The modulo is the same as the percentage symbol, but it’s important to remember it’s different meaning in this context.

Modulos are useful because they let us know if a number “fits” into a larger number, or if there will be a remainder. For example, how many eggs will be left over if I try and fit 56 eggs into crates of a dozen eggs?

int eggs = 56; int crateAmount = 12; int eggsLeftOver = eggs % crateAmount; Console.Write(eggsLeftOver); // prints 8

It can also be used to check if a number is odd or even. If a number is even, taking its modulo with 2 it will return a 0 and if it is odd it will return a 1:

int myNum = 85939824; Console.Write(myNum % 2); // prints 0, so number is even



You’re teaching computer science in a classroom and need to break up your students into teams.

Start by creating a variable named students that has the value 18.


You need to find a number that will go evenly into 18 (without a remainder) so that there are an even number of students. The groups should have more than 2 students in each group, but no more than 5.

Create a variable named groupSize. Enter a number between 3 and 5.


Inside of a Console.WriteLine() statement, use the modulo operator to see if students will divide evenly into groupSize. If it does not, change the value of groupSize until it does.

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