What you need: Casio DBC15-1 DataBank Calculator Watch (or similar), $60
Risk level: Low
Very few teachers will make you check your watch at the door. So, naturally, you should take advantage of this oversight. Though not as prevalent in the market as they once were, calculator watches can still be found online or at some RadioShacks or American Apparels. Besides offering you a calculator, watches like the Casio DBC15-1 DataBank gives you 150 pages for you to do whatever you want. Granted typing all your notes into a wrist watch will take a couple episodes of Curb, but it’s worth it.