You certainly don't need any special app. The TI program editor makes it extremely easy to store your notes as programs. HP calculators are a little more annoyi

You certainly don't need any special app. The TI program editor makes it extremely easy to store your notes as programs. HP calculators are a little more annoying for editing, but it's still easy to store text in a string variable. I did it on occasion, because sometimes there's such a ridiculous number of complex formulae that I'd rather spend my time practicing their use rather than memorizing them. The students who bank their whole grade on the notes in the calculator... typically can't pass anyway, because they don't know how to use the formulae.