Hello -
I just started doing [this mental math course] and decided to rip out a little app to generate problem sets for me to print out and work through. It's handy to simply fold up the paper (or a few) and stuff it in your pocket and pull it out throughout the day when you have some free time.
It's about 30 minutes of work and has no documentation. It's intended for you to modify the file in the params section and then F5 it to generate a file. As I learn more from this course, I expect to extend it properly. I didn't want to put too much work into it just yet. Given enough interest I can spend more time on the documentation.
Source [here]. Comments always welcome, if you have any.