A majority of mathematics textbooks are written in a rigorous, concise, dry, and boring way. On the other hands, there exist excellent, engaging, fun-to-read popular math books. The problem with these popular books is the lack of mathematics itself. This book is a blend of both. It provides a mathematics book to read, to engage with, and to understand the whys — the story behind the theorems. Written by an engineer, not a mathematician, who struggled to learn math in high school and in university, this book explains in an informal voice the mathematics that future and current engineering and science students need to acquire. If we learn math to understand it, to enjoy it, not to pass a test or an exam, we all learn math better and there is no such a thing that we call math phobia. With a slow pace and this book, everyone can learn math and use it, as the author did at the age of 40 and with a family to take care of.