Cleaned code a bit.

All I did was clean up the code a bit, instead of typing for example "num = num + y" you can simply have "num += y" which means the same thing but is shorter and makes the program easier to read quickly.

Your way works perfectly fine as well though, I just figured I'd leave a comment just in case no brought up the smaller alternative to you before that (from my experience) most people tend to use. :)