How to Check if a Number is Multiple of Another in Javascript

In this tutorial, you will learn how to check if a number is multiple of another in javascript. Whether a number is multiple of another or not, is decided by the remainder. If the remainder is 0, then the answer is yes. Otherwise, it is no.

Detecting whether a number is multiple of another or not is very easy, but it can be tricky if the number is coming from an input field because the value present in the input field is of string type. So first, we have to convert it into a number type using the `Number()` method and then perform any sort of calculations.

There are numerous ways to find whether a number is multiple of another or not. But for the sake of simplicity, we will only use the modulus (`%`) operator which is enough to get the job done.

In the following example, we will enter random numbers in both the input fields. Upon click of a button, we will check whether the number is multiple of another or not and display the result on the screen.  Please have a look over the code example and the steps given below.

HTML & CSS

• We have 4 elements in the HTML file (`div`, `input`, `button`, and `h1`). The `div` element is just a wrapper for the rest of the elements.
• The `innerText` for the `button` element is `“Check”` and for the `h1` element, it is `“Result”`.
• We have done some basic styling using CSS and added the link to our `style.css` stylesheet inside the `head` element.
• We have also included our javascript file `script.js` with a `script` tag at the bottom.
```<!DOCTYPE html>
<html lang="en">

<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>

<body>

<div class="container">
<input type="number" placeholder="Enter Number" id="numInput">
<input type="number" placeholder="Enter Divisor" id="divisorInput">
<button>Check</button>
<h1>Result</h1>
</div>

<script src="script.js"></script>
</body>

</html>```
```.container {
text-align: center;
}

button {
margin-top: 10px;
}

input {
display: block;
margin: 10px auto;
}

input[type=number]::-webkit-inner-spin-button,
input[type=number]::-webkit-outer-spin-button {
-webkit-appearance: none;
margin: 0;
}```

Javascript

• We have selected the `input` elements, `button` element, and `h1` element using the `document.querySelector()` method and stored them in `numInput`, `divisorInput`, `btnCheck`, and `output` variables respectively.
• We have attached a `click` event listener to the `button` element.
• In the event handler function, we are getting values from the `input` elements using `value` property. We are converting them into number type using the `Number()` method and storing them in the `num` and `divisor` variables.
• We are calling the `isMultiple()` method and passing `num` and `divisor` as parameters. This method will return a Boolean value.
• In the `isMultiple()` method, we are using the modulus (`%`) operator and ternary (`?`) operator to verify whether the `num` can be divided by the `divisor` and has a remainder of 0 or not.
• Depending upon the returned Boolean value, we will assign `“Yes”` or `“No”` to the `result` variable.
• We are displaying the `result` in the `h1` element using the `innerText` property.
```let numInput = document.querySelector("#numInput");
let divisorInput = document.querySelector("#divisorInput");
let btnCheck = document.querySelector("button");
let output = document.querySelector("h1");