Actually, the "For Dummies" books might be something to look into. I used them to refresh for my Calculus classes since they go into the basics and provide mathematical formulas and examples when necessary. Only good for the shear basics, though. If you get past all that and want to dive into relativity or quantum mechanics, you'll probably want a college textbook. Which you can find for dirt cheap if you pick out the older editions. Hell, I got a few lying around from a couple years ago that I don't use anymore, and wouldn't mind parting with for the cost of shipping. But probably easier just to go to a local used bookstore, especially if you live close to a campus.