# What is JavaScript remainder (%) Operator?

Are you ready to explore the intricacies of the JavaScript remainder operator %? Keep on reading!

In this article, you’ll understand its usage in various scenarios, such as determining even or odd numbers and implementing circular patterns.

Aside from that, you’ll also learn the difference between the remainder and modulo operations, especially when dealing with negative numbers.

This article includes practical examples and code snippets to illustrate these concepts.

## What is the JavaScript remainder (%) operator?

The remainder operator in JavaScript is represented by the % symbol, which is a mathematical operator that returns the remainder of a division operation.

It’s like when you were learning division in school and you were asked how much is left over after dividing one number by another.

For instance, if you divide 10 by 3, the quotient is 3 and the remainder is 1. In JavaScript, you can get this remainder by using the % operator like this: 10 % 3, which would return 1.

This operator is quite useful in various scenarios. For instance, it can be used to determine whether a number is even or odd.

If a number divided by 2 has no remainder (number % 2 === 0), then it’s an even number. If there’s a remainder of 1 (number % 2 === 1), then it’s an odd number.

Another interesting use of the remainder operator is in implementing circular patterns or “wrap-around” logic, often referred to as clock arithmetic or modular arithmetic.

Imagine a clock – after 12, we don’t go to 13, but back to 1. This “wrapping around”can be achieved using the remainder operator.

Lastly, it’s important to note that while the remainder operator behaves similarly to the modulo operator found in some other programming languages, they can give different results when dealing with negative numbers.

In JavaScript, the remainder operator always takes the sign of the dividend (the number being divided).

## How to use the remainder (%) operator?

The JavaScript remainder operator % is used by placing it between two numbers.

The first number is the dividend (the number to be divided) and the second number is the divisor (the number to divide by).

The result of the operation is the remainder of the division.

Here’s an example:

let sampledividend = 100;
let sampledivisor = 3;
let remainder = sampledividend % sampledivisor; ✅

console.log(remainder);

Output:

1

As you can see 100 is divided by 3, which equals 33 with a remainder of 1. So, 100 % 3 returns 1.

As we mentioned earlier, the remainder operator % operator is particularly useful in various scenarios, such as determining whether a number is even or odd.

If a number divided by 2 has no remainder (number % 2 === 0), then it’s an even number. If there’s a remainder of 1 (number % 2 === 1), then it’s an odd number.

Here’s an example illustration:

function isEven(num) {
return num % 2 === 0;
}

console.log(isEven(50)); // Output: true ✅
console.log(isEven(53)); // Output: false

As you can see, the function isEven checks if a number is even by using the remainder operator.

If the number modulo 2 equals 0, it means the number is evenly divisible by 2, so it’s an even number, and the function returns true. Otherwise, it returns false.

## What is the difference between remainder and modulo?

In mathematics, both the remainder and modulo operations involve division and deal with what’s left over after division.

However, they handle negative numbers differently.

When you divide one number by another, the remainder is what’s left over after division. For example, if you divide 10 by 3, you get a quotient of 3 and a remainder of 1, because 3 goes into 10 three times with 1 left over.

On the other hand, the modulo operation also involves division but it’s a bit different. The result of a modulo operation is the remainder of the Euclidean division (also called division with remainder) where the quotient is rounded towards negative infinity.

The key difference between the two lies in how they handle negative numbers.

Consider -10 divided by 3. In normal division, this would give you a quotient of -3 and a remainder of -1. This is because -3 times 3 is -9, and when you subtract -9 from -10, you get -1.

However, with the modulo operation, the result would be 2. This is because, in modulo operation, the remainder can never be negative. The quotient is rounded towards negative infinity to make the remainder positive or zero.

So -4 times 3 is -12, and when you subtract -12 from -10, you get 2.

So while both operations might seem similar at first glance, they can give different results when dealing with negative numbers. It’s always important to know which operation is used in your programming language of choice.

## Conclusion

In conclusion, the JavaScript remainder operator % is a useful tool that can be used in a variety of programming scenarios.

It provides a way to calculate the remainder of a division operation, which can be useful in determining whether a number is even or odd, implementing circular patterns, and normalizing angles in computer graphics.

However, it’s important to understand the difference between the remainder and modulo operations, especially when dealing with negative numbers.

The remainder operator always takes the sign of the dividend, while the modulo operation always results in a non-negative remainder.

We hope this article has provided you with enough information to understand the JavaScript remainder operator.

If you want to explore more JavaScript topics, check out the following articles:

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