<? // perfect number checker v1.0 // returns true if the number is perfect // perfect numbers are equal to their proper divisors function is_perfect($number) { for ($n = 2; $n <= sqrt($number); $n++) { if (!($number % $n)) { $d += $n; if ($n <> $number / $n) $d += $number / $n; } } return ++$d == $number; } // * example use - display perfect numbers below 100 * // for ($n = 1; $n < 100; $n++) if (is_perfect($n)) echo $n . '<br />'; ?>