He starts at the beginning with math and works his way up. Your average IT/programmer guy will probably not have read this book, but it covers all the basics. Think of it as a replacement for a CS degree or at least the lower division courses.

I liked the books as references. I really only worked through most of Volume 1. followed by a detour into Concrete Mathematics. I have made frequent use of Volume 2 and Volume 3 as reference volumes. In college they were invaluable when professors selected some awful textbooks by providing explanations of certain algorithms and concepts and data structures.