I was thinking of doing that with 7s. I like how 7s wreck the
   decimal, octal and hexi bases alike. Witness anything in 7ths.
   1/7, 2/7, 3/7... try making nice clean decimals? Nope. It won't.
   Wrecks Base 10. Love it! Also, I'm weak on 7s. I'm OCD by nature
   but I found by "going opposite", it keeps it at bay. Example: I
   keep my areas messy to combat the need to be super-organized. it
   works.