This book is a good general reference for the technical professional who travels. A good variety of formulas and commonly referenced data makes this useful to someone who has experience solving problems, but just forgot the formula. There is little explaination of the subject matter, so it has limited use to the uninitiated. Still, the unit conversions, area formulas and good coverage of mathematics makes it valuable to the person who only occasionally has to make simple calculations. It also should sufficiently intimidate anyone who might think that solving engineering problems is fun and easy. The numerous, well scattered blank pages are useful for writing in your own formulas or notes, and the small size assures that you will take this one with you. I am buying a second because my brother (a technical salesman) ran off with mine.