An anonymous reader writes: I have a secret. In high school I failed two out of three years of math classes and eventually dropped out of school completely. Although dropping out was the most foolish thing I have ever done, I am not dumb. I earned my general equivalency diploma as soon as was legally possible and from there went on to college and beyond. That was many years ago and my most basic algebra, trigonometry, and geometry skills are slipping away at an alarming rate. I'm looking for a self-guided course covering the equivalent of 4 years of high school mathematics including calculus. My math skills are holding me back. How can I turn this around?