Question

How to check if a number is strong number or not in PHP

Answer 1

// Strong numbers are the numbers that the sum of factorial of its digits 
// is equal to the original number
 
// 145 is a strong number: 1 + 24 + 120 = 145
  
$n = 145;
$sum = 0;
 
$tmp = $n;
 
while ($n != 0)
{
    $reminder = $n % 10;
    $sum = $sum + factorial($reminder);
    $n = (int)($n / 10);
}
if ($sum == $tmp)
    echo $tmp . " is a strong number<br />";
else
    echo $tmp . " is not a strong number<br />";
    
                
function factorial($n)
{
    $fact = 1;
 
    for ($i = 2; $i <= $n; $i++)
        $fact = $fact * $i;
 
    return $fact;
}

/*
run:
 
145 is a strong number
  
*/

 

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