I don't use any maths software on my tablet, but I do use a few apps to help stay organised. Notability
by Gingerlabs is my choice for note-taking – the main reason for this was that at the time I bought it, the main competitor Goodnotes
didn't support my choice of cloud storage backup Google Drive
– but there are a variety of well-designed apps out there and I'd encourage you to take a look at all the options. If you like to keep electronic copies of your textbooks, then PdfExpert
is a popular app for reading and annotating pdfs. While many note-taking apps have this functionality, somebody who frequently uses large pdfs will want the extra features and user experience improvements offered by a dedicated pdf management app.