Question

How to sum the digit of a factorial of a number in PHP

Answer 1

function sumDigits($num) {
    $sum = 0;
    
    while ($num != 0) {
        $sum += $num % 10;
        $num = intval($num / 10);
    }
    
    return $sum;
}

function factorial($n) {
    if ($n == 1 || $n == 0) {
        return 1;
    }
    return $n * factorial($n - 1);
}

$number = 9;

$result = factorial($number);

echo "factorial = " . $result . "\n";
echo "sum digits = " . sumDigits($result) . "\n";


   
/*
run:
    
factorial = 362880
sum digits = 27

*/

 

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