Unfortunately, choosing a calculator is a touch complicated if you're in school.
For general purpose electronics use, any scientific calculator will do. I like the Casios, FX 260 is as close to ones I used heavily in school in the 1980s [ older Casios are more durably made and keys laid out better, I still use my 30+ year old college Fx-100 today].
This is really for bench fixups, back of napkin designs or estimates. Portability, maintenance free, and low cost are most important, this is about $8 at Walmart or $11 at Amazon, fully solar no batteries. Its very light too, and wont' load your shirt pocket, so I have 3: one in the lab, one in my work bag and one in the living room:
For just $1-3 more you can get another with gobs of added functions, even graphing, but it also makes the calculator bigger, adds more keystrokes, and hard to shirt pocket.
You don't really need more than ~ 8 bit accuracy for making back of envelope calculations. if you need to do more complex or accurate calculations, its best to use a PC so the outputs are fed into SPICE or other simulator, has superb graphing, and the free Windows calculators provide all the basics. Also if you track calculations with a 'paper tape' on a PC its far easier to manipulate.
For school, learning math concepts and being that some classes do not allow you to use a PC, PC provides far better graphing capabilities, you have to go with what the class recommends.