How to Find Cube of a Number in Javascript

In this tutorial, you will learn how to find cube of a number in javascript. To get the cube of a number, we have to multiply the number by itself thrice. For example, the cube of 3 is 9, as 3 × 3 x 3 = 9.

Calculating the cube of a number 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 do the calculation.

To calculate the cube of a number, we can make use of the Math object.  This object contains a lot of methods and properties which can help us in various mathematical operations. One of those methods is the pow() method which will take a base and an exponent as a parameter and returns a number representing the given base taken to the power of the given exponent.

In the following example, we have an input field in which we will enter a random number. Upon click of a button, we will get its cube and display that 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 “Cube” 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">
    <button>Cube</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 element, button element, and h1 element using the document.querySelector() method and stored them in input, btnCb, and output variables respectively.
  • We have attached a click event listener to the button element.
  • In the event handler function, we are passing the value of the input element to the Number() method and storing the number in the num variable.
  • We are calling the pow() method to get the cube of num and storing it in the result variable.
  • We are displaying the result in the h1 element using the innerText property.
let input = document.querySelector("input");
let btnCb = document.querySelector("button");
let output = document.querySelector("h1");

btnCb.addEventListener("click", () => {
  let num = Number(input.value);
  let result = Math.pow(num, 3);  
  output.innerText = result;
});
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