our @codes = (
    sub {},
    sub {
        my ($n1, $n2) = @_;
        print "The Sum of the Numbers $n1 + $n2 is ", $n1 + $n2, "\n";
    },
    sub {
        my ($n1, $n2) = @_;
        print "The Difference of the Numbers $n1 - $n2 is ", $n1 - $n2, "\n";
    },
# . . .
);

$codes[$sign]->($num1, $num2);