JavaScript: Find a perfect number

Last update on May 30 2022 10:02:34 (UTC/GMT +8 hours)

JavaScript Function: Exercise-12 with Solution

Write a JavaScript function which says whether a number is perfect.

Note : According to Wikipedia : In number theory, a perfect number is a positive integer that is equal to the sum of its proper positive divisors, that is, the sum of its positive divisors excluding the number itself (also known as its aliquot sum). Equivalently, a perfect number is a number that is half the sum of all of its positive divisors (including itself).
Example : The first perfect number is 6, because 1, 2, and 3 are its proper positive divisors, and 1 + 2 + 3 = 6. Equivalently, the number 6 is equal to half the sum of all its positive divisors: ( 1 + 2 + 3 + 6 ) / 2 = 6. The next perfect number is 28 = 1 + 2 + 4 + 7 + 14. This is followed by the perfect numbers 496 and 8128.

Pictorial Presentation:

Sample Solution: -

HTML Code:

<!DOCTYPE html>
<html>
<head>
<meta charset=utf-8 />
<title>Find a perfect number</title>
</head>
<body>
  
</body>
</html>

JavaScript Code:

function is_perfect(number)
{
var temp = 0;
   for(var i=1;i<=number/2;i++)
     {
         if(number%i === 0)
          {
            temp += i;
          }
     }
   
     if(temp === number && temp !== 0)
        {
       console.log("It is a perfect number.");
        } 
     else
        {
       console.log("It is not a perfect number.");
        }   
 } 
is_perfect(28);

Sample Output:

It is a perfect number.

Flowchart:

Live Demo:

See the Pen JavaScript - Find a perfect number-function-ex- 12 by w3resource (@w3resource) on CodePen.

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Next: Write a JavaScript function to compute the factors of a positive integer.

JavaScript: Tips of the Day

How to insert an item into an array at a specific index (JavaScript)?

What you want is the splice function on the native array object.

arr.splice(index, 0, item); will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert). In this example we will create an array and add an element to it into index 2:

var arr = []; arr[0] = "Jani"; arr[1] = "Hege"; arr[2] = "Stale"; arr[3] = "Kai Jim"; arr[4] = "Borge"; console.log(arr.join()); arr.splice(2, 0, "Lene"); console.log(arr.join());

Ref: https://bit.ly/2BXbp04