Addition, subtraction, multiplication and division!
Small Math Spinner
Print 2 end caps, 4 numbers, one math symbol, one equals and one center piece. For the original small size, you'll have to rearrange the sections for division.
Large Math Spinner
For those with larger build platforms, you can print the centerLarge and print 6 extra number sections to do larger math problems.
12-7-2013 - UPDATE
I added 'fixed' files in case your printer sees the models scaled down. I didn't detect an issue on my end but I re-exported them out anyway & then triple checked in netfabb.