Author here, it's probably what I did, but i am sure i also had to memorize quite a few radicals, and also multiplying numbers up to 40X40 + other tricks to multiply fast.
Any idea where I can get more English questions like the ones you’ve listed? They’re quite enjoyable! Though some of your translations are a bit off:
> A cube has one of its sides 2cm. The total area of the cube is ...
Pretty sure you mean “surface area”.
I plan to put them into a github repo this month.
Sorry for the translations. I will try to check them again, and maybe to some corrections.
Here's another tiny little nitpick if you want to improve your translation a bit more: In English we don't say "inequation", we say "inequality".