The % operator is used to return the remainder if one number were to be divided by another. So 5 % 2 would return 1, because 2 goes into 5 twice, with 1 left over. Another example is 10 % 2 which would return 2. 4 goes in twice, with 2 left over.
So x % n == 0 just means that there is no remainder (it fits perfectly).
Hope that helped!
Oh, ok. The reason why I stick with 2.5 is because of WConio, and I haven't been able to find out how to get it to work with 2.6 yet. I'd need to modify the .pyd file for it, but I have no idea how to do that (the file looks like gibberish to me when I open it in Windows). http://newcenturycomputers.net/projects/wconio.html