Either 0 or any positive whole number less than 9
So the possibilities are: 0, 1, 2, 3, 4, 5, 6, 7, 8
Anything larger will wrap around. For example, 12/9 = 1 remainder 3. If you had 12 cookies and 9 friends, then each person gets 1 cookie and there are 3 left over.