Just by manually writing the same text as you would normally just read. You could improve. I guess the understanding is tied together with the memory. So if you could remember the text better. Your brain will have an easier time to process the data and understand it.
This method really goes with everything you want to learn.
So the idea is to encode the data in brain memory.
You can configure Linux MATE to capture the screenshot area with shift-Print. With this you just capture the area of a handwritten photo of the math formulas. Then do some basic adjustments for contrast and light and color.
Another idea I have is to run jupyter notebook (iPython) on a raspberry pi. Just connect a bluetooth keyboard the the phone and you can run the notebook, and console programs in the browser of the phone. This way you don’t need VNC on the phone. Just a browser will do. Octave will run the terminal which could be quite handy.