If you are an engineer or scientist you might know one mathematical packages. And the Octave is a prety powerfull one. It’s a command line program (but with command line history and with other features). It can be an disadvantage for some but on Ben’s small screen it is an advantage. And most of users of these packages used them by typing of equations like “a=inv(b) + 3*c” so command line interface is natural here (of course there are graphical interfaces for the Octave but none of them is ported to NanoNote).
There is still one (big) limitation: graphing features of the Octave now are not available on the NanoNote. But David is working hard on this remaining problem. In meantime, there is at least an port of the Gnuplot graphing software.
If I understand David’s explanation of the difficulties then the problem is that probably nobody tried to run the Octave together with the Gnuplot on a linux framebuffer for a very long time (probably because everyone is using X Window System for desktop tasks).
Anyway, availability of the Octave allows to use the NanoNote as a very powerfull programmable calculator (with matrices and much more). One can also use many Octave extensions to get additional capabilities. It is even possible to use finite element software CALFEM inside the Octave (I have tried this one and it just works).