Armstrong Number in JavaScript

May 6, 2021 admin

A positive number is called an Armstrong number if it is equal to the sum of the cubes of its digits, for example, 0, 1, 153, 370, 371, 407, etc.

In other words, the following equation will be verified

xy..z = xⁿ + yⁿ + ….. + zⁿ

n is the number of digits

For example, 370 is a 3-digit Armstrong number

370 = 3³ + 7³ + 0³
= 27 + 343 + 0
= 370

Now we will see Armstrong’s implementation in Javascript.

Program to check if the given number is an Armstrong number

<!doctype html>
<html>
   <head>
      <script>
         function armstrong()
         {
             var num = Number(document.getElementById("myInput").value);
             let sum = 0;
             //store the number to check later
             let tmp = num;
             //Extract each digit from the number
             while(num > 0){
                  //retrieve the last digit
                  let d = parseInt(num % 10);
                  //find the cube
                  d = d ** 3;
                  sum = sum + d;
                  //convert float to Integer
                  num = parseInt(num / 10);
             }
             if(tmp === sum)
             {
                  alert("Armstrong number");
             }
             else
             {
                  alert("Not an armstrong number");
             }
         }
      </script>
   </head>
   <body>
      Enter a number: <input id="myInput">
      <button onclick="armstrong()">Check</button>
   </body>
</html>