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;
}
