Can I turn my mac keyboard into a number pad?

I have a late 2008 MacBook Pro that runs on Lion. Is there any way (without using my iPod/iPhone/iPad or using a wireless number pad) to be able to turn my current keyboard into a number pad; for some reason I want to say someone told me a while back that there was a way you could do it with Fn if you turned something on in your control panel however I don't remember the tip. Any help would be greatly appreciated.

Also, this weekend I'm purchasing a new MacBook Pro that will run Mountain Lion, is there a way I can do the Number Pad on it?

Yes you could write a program in C++ that would fix that.