In this article, you’ll learn how to **check if a number is a multiple of another in JavaScript** by using the remainder operator. Let’s go into detail now.

## Check if one number is multiple of another in JavaScript

**Using a remainder operator **`(%)`

`(%)`

**Syntax:** `x % y`

The remainder operator (or sometimes called the modulo operator) divides two numbers and returns its remainder. By that logic, if a number when divided by another number returns a `0`

as its remainder, the former number is therefore a multiple of the latter number.

As such, the code would look something like this:

**Code:**

const n1 = 10; const n2 = 2; const n3 = 3; function isMultiple(divided, divider) { return divided % divider === 0; // If the remainder is 0, it's a multiple } // Check n1 and n2 if (isMultiple(n1, n2)) { console.log(`${n1} is a multiple of ${n2}`); } else { console.log(`${n1} is NOT a multiple of ${n2}`); } // Check n1 and n3 if (isMultiple(n1, n3)) { console.log(`${n1} is a multiple of ${n3}`); } else { console.log(`${n1} is NOT a multiple of ${n3}`); }

**Output:**

```
"10 is a multiple of 2"
"10 is NOT a multiple of 3"
```

**Checking if a number is a multiple of several other numbers**

That’s great, but what if you wanted to check if a number is a multiple of several numbers? For example: How do you check if every number in an array has a number as its multiple or which has that number as a multiple? You could do it manually, but that can be monstrously tedious. An automated method is required and can be found in using a function in combination with rest parameters.

The rest parameter syntax `(...)`

allows a function to have a practically infinite number of parameters, which can then be iterated like an array. Iterating over the parameters can be done with a `for...of`

loop, which specifically iterates over collections like arrays.

Using that method, we can check if a number is a multiple of several numbers; as such:

**Code:**

function isMultipleOf(product, ...numbers) { for (const number of numbers) { // If the remainder is 0, return true if (product % number === 0) { return true; } } return false; } console.log(isMultipleOf(12, 1, 4, 3, 2, 6)); console.log(isMultipleOf(12, 5));

**Output:**

```
true
false
```

Additionally, you use an array as a parameter, as long as you use a spread syntax `(...)`

with it. The spread syntax takes a collection of items (e.g., arrays, objects) and converts it into a list of arguments (i.e., parameters). A spread syntax has other utilities, which you can read about here. For example:

**Code:**

function isMultipleOf(product, ...numbers) { for (const number of numbers) { // If the remainder is 0, return true if (product % number === 0) { return true; } } return false; } console.log(isMultipleOf(12, ...[1, 4, 3, 2, 6])); console.log(isMultipleOf(12, ...[5]));

**Output:**

```
true
false
```

Additionally, if you want the function to instead return every number that has the number as its multiple, you can do like below:

**Code:**

function isMultipleOf(product, ...numbers) { const arr = []; for (const number of numbers) { // If the remainder is 0, add the number to the list if (product % number === 0) { arr.push(number); } } return arr; } console.log(isMultipleOf(12, ...[1, 4, 3, 2, 6])); console.log(isMultipleOf(12, ...[5, 3, 6, 7, 1]));

**Output:**

```
[1, 4, 3, 2, 6]
[3, 6, 1]
```

**Summary**

To **check if one number is multiple of another** in JavaScript, you can use the remainder operator `(%)`

and check whether the number returned is `0`

or not. If the number returned is `0`

, then the number is a multiple of the other.

**Maybe you are interested**:

- Check If A Number Is Between Two Numbers In JavaScript
- Check if a Number is NaN in JavaScript
- Check if a Number is a Negative Integer in JavaScript

Hello, my name is Davis Cole. I love learning and sharing knowledge about programming languages. Some of my strengths are Java, HTML, CSS, JavaScript, C#,… I believe my articles about them will help you a lot.

**Programming Languages**: Java, HTML, CSS, JavaScript, C#, ASP.NET, SQL, PHP