[Rebecca Virnig] I used this book in high school and absolutely loved it. It's very skimpy on proofs, and really should not be used for that sort of insight. However, in terms of understanding how to apply various mathematical concepts it's wonderful. It has a large number of graphs, examples, and easy reference tables. It covers all the algebra, trig, and cartesian geometry that any good high school math sequence should deal with. I have used it for years as a reference book (e.g., what exactly is Cramer's rule again...) Solutions to a number of the problems are in the back, and the problems are not entirely applications.

These three little white books come from the Soviet correspondence school in mathematics, run by I. M. Gelfand for interested people of all ages in the further reaches of the USSR. Rather than trying to be artificially "down-to-earth" in the way Americans do, Gelfand simply assumes that you can understand the mathematics as it's done (and avoids the formal complexities mathematicians are inured to). YSP and SESAME give these out by the carload to their students, who mostly love them. TMoC is notable for its intriguing four-axis scheme for making flat graphs of \(\mathbb{R}^4\). Overall a fresh, inspiring look at topics we take for granted, and a good thing to recommend to bright younger students or friends (or parents!)