function q4() { $highestPalindrome = null; for ($i = 999; $i > 99; --$i) { for ($j = 999; $j > 99; --$j) { $value = $i * $j; if ($value < $highestPalindrome) { break; } if (Str::isPalindrome($value)) { $highestPalindrome = $value; } } } return $highestPalindrome; }