1. Even number minus even number, is it always even number ?
2. odd number minus odd number, is it always odd number? Or is it ever odd?
3. is zero even, odd, or real? If no then what?

Have you tried to consider each of those cases? What do you think? Tell us that, we'll see how we can help you the best possible way. :)

Yeah. Put those to the test and see what results you yield.