Working with large numbers in PHP

Question

To use modular exponentiation as you would require when using the Fermat Primality Test with large numbers (100,000+), it calls for some very large calculations.

Whe

Answer 1

0;$i--){
        $var = $int1[$i-1] + $int2[$i-1] + $carry;
        $var = str_pad($var, 2, '0', STR_PAD_LEFT);
        $var = (string) $var;
        $carry = $var[0];
        $str = $str . $var[1];
    }
    $res = strrev($str.$carry);
    echo ltrim($res,"0");
}
add($int1,$int2);
?>