February 23, 2022

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

By Krishnaa JavaScript Questions 0 Comments

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">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <link rel="stylesheet" href="style.css">
  <title>Document</title>
</head>

<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;
  padding: 10px 20px;
}

input {
  display: block;  
  margin: 10px auto;
  padding: 10px 20px;
}

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");

btnCheck.addEventListener("click", () => {
  let num = Number(numInput.value);
  let divisor = Number(divisorInput.value);
  let result = isDivisible(num, divisor) ? "Yes" : "No";
  output.innerText = result;
});

function isMultiple(num, divisor) {
  return num % divisor === 0;
}

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