Eg Numeric integral / differential calculation, trigonometric and inverse trigonometric functions, recurring decimal. Or many simple functions for everyday applications. Currency conversions, statistics, etc.
Mathematicians are more than happy with the part. In any case, I have the app on the Google Nexus 10, there is only one simple calculator. In the tablet the already looks something like NASA. Very good app, cheaper like a calculator, and probably much better. It benefits from the input possibilities of a tablet, or large smartphones (phablets such as Samsung Note).
The app does not need unnecessary rights, and you will get along with the functions until the end of life. Only new-hitting scientific findings in mathematics might what to change the functionality.
