I know those are easy to find on children's education materials, but the keyword here is simple. Anything kiddie, requiring too many clicks or that takes 3 seconds is off the table.

I kinda need to brush up on my super basic reasoning. In part, because a grown man should know the time table by heart, and in part, because I wanna convince myself that I did not get brain damage after being hit by a car (there's really nothing indicating that, I'm just paranoid).

I'm looking for something simple that presents me with the multiplication table and or simple calculations to answer under a time frame. The requirement for iOS is that my computer is broken.

And it really can be super simple, even something I open from a mobile web browser or transfer to my Kindle.

Additionally: there is no need for if to be an app. A huge list of exercises (with answers) would be greatly helpful.

Thanks!

I'm interested in the subject, but don't know where to begin investigating it. I tried to look over the code for SeDuMi, but it is much more massive than I had realized. I have a background in mathematics, if anyone can point me towards a textbook.

Does there exist a function that does not include any trigonometric function in its definition that has similar properties (periodicity, for instance) as trigonometric functions? I can't think of any, and this strikes me as a bit surprising.

Edit: I thought of a simple answer: piecewise functions can achieve this!