Something

#!/usr/bin/perl
print "Please insert your first number you want to be multiplied\n";
$first = <STDIN>;
if ($first eq "\n") {
        print "That was just a blank line!\n";
} else {
        print "Please insert your second number you want to be multiplied\n";
}
$second = <STDIN>;
if ($second eq "\n") {
        print "That was just a blank line!\n";
} else {
        print "=\n";
        print $first * $second;
}
print "\n";