If you have ever wanted to learn some higher mathematics, but don’t want to slog through the long tedious proofs associated with calculus and analysis, then you might like this gem of a book by Edwin H. Connell. He is an emeritus mathematics professor at the University of Miami, and has graciously made his book available for download on the web.
I am currently taking a course in abstract algebra and thus not well qualified to review the book yet, but I have read the first two chapters and find that it presents the material succinctly and quite readably. It is definitely at the undergraduate level and probably accessible to ambitious high-school students as well. I also agree wholeheartedly with the following comment which comes from his web site.
The present situation with college textbooks is a national disgrace. Textbooks are too big and too expensive.