use bigint;

#for ($i = 1020304050607080900; $i < 192939495969798990; $i += 10) {
for ($i = 1010101010; $i < 1389026623; $i+=10) {
    $res = ($i ** 2);
    if ($res =~ m!1\d2\d3\d4\d5\d6\d7\d8\d9\d0!) {
        print "$i ^ 2 = $res\n";
        exit;
    }
}