I have fond memories of the TI-89 - all the power of a TI-92, but the same form factor as the TI-83/84, so it wouldn't raise much attention. Having a computer

I have fond memories of the TI-89 - all the power of a TI-92, but the same form factor as the TI-83/84, so it wouldn't raise much attention. Having a computer algebra system in my handheld calculator got me all the way from pre-algebra to intro diff eq in high school. It's hard to say whether it was unfair, but being able to try algebra and calculus things out on the CAS really helped me explore and understand concepts.