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PHP | Check if a number is Perfect number

A perfect number is a number if it is equal to the sum of its factors,that is original number is equal to sum of all its factors excluding the number itself. We have already discuss how to check if a number is perfect or not in this article. In this article we will discuss about how to do the same in PHP.

Examples:

Input : 6
Output : Perfect Number
Explanation: factors of 6 are 1, 2, 3, 6
             sum of its factors (excluding the 
             number itself) = 1 + 2 + 3 = 6 

Input : 24
Output : Not Perfect Number
Explanation : factors of 24 are 1,2,3,4,6,8,12,24 
              sum of its factors(excluding the 
              number itself) = 1 + 2 + 3 + 4  
                                + 6 + 8 + 12 = 36



The idea to this is we will traverse through each number in the range [1,N) and check if it is a factor of the given number N. If it is a factor, we will add this number to a variable $sum. At the end is the variable $sum is equal to the original number then the the given number is a Perfect Number.

Below is the implementation of above idea in PHP:

<?php
// Function to check if a number is perfect
function isPerfectNumber($N)
{
    // To store the sum
    $sum = 0;
       
    // Traversing through each number
    // In the range [1,N)
    for ($i = 1; $i < $N; $i++)
    {
        if ($N % $i == 0)
        {
            $sum = $sum + $i;
        }      
    }
      
    // returns True is sum is equal
    // to the original number.
    return $sum == $N;
}
   
// Driver's code
$N = 6;
  
if (isPerfectNumber($N))
    echo " Perfect Number";
else
    echo "Not  Perfect Number";
?>

Output:

Perfect Number


This article is attributed to GeeksforGeeks.org

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