Let's face it: It's a little embarrassing to pull out your phone at the restaurant for some sixth grade math ... The calculator on your smartphone isn't the only quick way to calculate a tip.

or MATH 2000 (brief calculus). The TI-83 (not Plus), TI-86, TI-92 and the TI-92 Plus are no longer manufactured. Certainly these older calculators may still be used in courses allowing any calculator.