Pretty much anything. If you want it to come out evenly, try 1,3,5 or 15.
18
1.4667
9.6667
15 divided by one is 15. Anything divided by one is that same thing. One is the identity.
37.5 divided by 2.5 = 15
64
10.6667
150
1.1333
55.4667
9.7333
15 is the highest number 15 can be divided by evenly.