this book is a collection of class notes from the author. Those class notes are presented in the form of mathematical derivations of important and assorted formulas used in engineering. There is no specific sequence in the content and the chapters are divided by branches of the mathematics used in engineering (like Calculus, Statistics, etc). The book is not intended to be a book about mathematics or engineering, neither is a complete reference for the derivations of all formulas that exist in the subjects. Rather, is a small set derivations that had a positive feedback from colleagues and students along the teaching years of the author.