As far as basic math goes, I could do with a quick refresher. Some things I have forgotten, like some of the operations with fractions, but nothing that couldn't be recovered in about a week.
However, most of the books I was taught with taught by rote memorization of arithmetic algorithms...
So a few years after school, I managed to forget most of what I learned in math class. I'm planning on reteaching myself from elementary arithmetic to calculus. I'm requesting a sequence of books to get me there. Looking for something rigorous, that actually explains why algorithms work, etc...