These are calculators that do not have CAS. No need to waste money on a TI89, TI92, or TINspire. They are not permitted on the ACT and typical university examinations (when you need a CAS in college its better and cheaper to use software rather than a $220 calculator anyway). On the AP Calculus exams, only one out of three questions permit the use of a calculator, and 33.3% is not a passing score. Calculators are needed to introduce numerical approaches where an antiderivative may not exist. They can be a tool that one might need some training to harness its power to find solutions in math, engineering and science. Discovering patterns with a calculator can deepen the understanding of a theorem. So to strengthen your arithmetic and algebra skills, here are some excellent choices.
If you have one of these already, keep it! If you lose it or want an upgrade, you get more bang and performance with a Casio (if you don't mind relearning where the buttons and features are). My favorite for Calculus is the Casio fxCG50 (sooo much faster graphing and the root/intersection finding) For AP Stats, I still favor the TI84 because I like defining new lists within the list editor. This preference might be the bias I have for using the TI for so long. If you won't be taking any AP Math exams, the numworks calculator is an emerging software defined calculator is work a look. Right now it is a early version (15.3.0), and you cannot store the intersection points, and there is no inference app yet. It is small, light, bright, quick, and I like button layout (but yellow is terrible choice).
Model  Pros  Cons 

TI84 CE 


Casio fxCG50 


Casio fx9750giii
(gen 3 new 2021) 


TI84 Plus 


TI83 Plus 


(Fr. Chris will be happy to teach you how to use it if you buy him one! (He has a limited budget, so he can't buy every one on the market, but is always happy to figure out how to use a new toy!)