Lesson 27: The Modulus Operator

In some of the earlier lessons, we went over the 4 most used math operators used in Java.  Those four included:


Now that we have a little practice underneath our belt in Java, we are going to introduce a new math operator that you’ve probably never seen.  This new operator is called: the modulus operator %.  

The modulus operator uses division and outputs a result.  However, the result is not the dividend.  Instead, it is the remainder.  In other words, it is the number left over if a number does not divide evenly.  Let’s look at an example to better understand.

In Example 1, we can see the equation 9 % 4.  As we well know, 9 is not evenly divisible by 4.  Therefore, because we are using a modulus operator, we know that 4 goes into 9 twice and leaves us with 1 leftover.  Hence, the result for example 1 should be 1.

In Example 2, we have 9 % 3.  Knowing that 9 is evenly divisible by 3, we can determine that there will not be a remainder.  Therefore, we know that the result for example 2 should be 0.

Let’s take a look at the output below:

Sure enough, we had a remainder of 1 for the first example, and no remainder for the second example.  

Although we haven’t seen any opportunities for a modulus operator yet, in future lessons we will see it used with more complex math problems.

GitHub link.

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