This app was mentioned in 5 comments, with an average of 9.40 upvotes
There has been complete TI calculator emulator since ages ago. On top of that a pure math software in smartphone is vastly superior than any calculator. (And cheaper. Those disposable freebie smartphone at walmart can run circle around TI calculator.)
Maxima on android:
https://play.google.com/store/apps/details?id=jp.yhonda
old youtube. TI emu on android.
There is always Maxima, if you want to do real Math on Android. It can do pretty much anything.
Maxima on Android gives you a great open source symbolic math program with a long history.
i doubt it, but would be happy to be corrected on this.
If you have an Android device, however, you could run Maxima on it: Maxima on Android.
(There's also Maxima Online, for those who'd like to try it out.)
EDIT: Oh, i just remembered classic calculators like the HP 41C; they might be able to be programmed to do such things. (It's been quite a while since i last programmed one!)