Your sub add is OK, but multiply seems to be just a copy of add, so it will not multiply.

You have also continued to ignore previous good advice, starting from mrborisguy's - You need 3 arguments to your program - the Operation to perform and at least 2 operands.

We will continue to help you, and it is OK to post more code and questions here - in fact that is encouraged - but you need to show some effort, and regard for good advice.