# How Arithmetic Works in JavaScript (Examples Included)

In case you don’t know, arithmetic is just taking 2 or more numbers and adding, subtracting, multiplying, dividing, etc. with them.

It looks like so:

``1 + 2 * 5``

``11``

That + and * you see there are what JavaScript calls operators.

Here’s where some people might make the mistake of first adding 1 and 2, then multiplying it by 5. Which isn’t how arithmetic works.

The correct way is to first multiply 2 and 5 then add that to 1. This is due to a mathematical concept called the precedence of operators. It’s a rule.

There’s plenty of information and charts to help guide you onto what operator takes “precedence” over what. Just understand that * must go before +.

If you want to really control what goes before what and bypass the precedence rule, you can insert parentheses like this:

``(1 + 2) * 5``

These parentheses force the addition of 1 and 2 first, then multiplying that by 5 which gives us a totally different result:

``15``

Here’s another note to keep in mind, some operators have equal precedences like multiplication and division. Here, it doesn’t matter which one goes first, the results are the same.

Let’s do a little quiz.

## Arithmetic Quiz

### Example 1

``32 + 4 * 3 - 3``

``41``

Because of precedence, it looks more like 32 + (4 * 3) – 3. So it starts with the 4 multiplied by the middle 3. Then, the result of that is added to 32, and then finally 3 is subtracted from the overall.

## What is the remainder or modulo operator?

This one’s special. The symbol for the remainder or modulo operator is %.

Its precedence is equal to * and /.

It produces the remainder of dividing 2 numbers.

Let’s test this:

## What’s the remainder/modulo for these numbers?

### Example 1

``12 % 3``

``0``

The reason for this being 0, is because once you divide 12 by 3, you are left with nothing else “remaining.”

Let’s take another example, this time with something remaining.

### Example 2

``12 % 5``

``2``