I am using this book as a "practice-first" guide to mathematics for the guy in his thirties, who struggles to understand why his high education was not done right 15 years ago, and do it so by himself this time.<br>Accompanied by the lectures on the subject (search the title on youtube), this is likely the best book on math out there for motivated unexperienced reader.<br>It will throw you to many practical fields of mathematics, and, having enough time, one can continue wandering and hunting for different subjects while eating this dish chapter by chapter (or lecture by lecture). For me, who has the luxury of not following any education plan, this is a delicious experience.