This book removes the mystery and pressure from calculations by equipping readers with the tools they need to understand calculations and how they work. This is done by using straight-forward language and showing fully worked out, rig-based examples throughout. The book comprises of mini lessons which are never more than two pages long and a complete lesson is always in view when the book is open in front of you. Lessons progress in a logical manner and once the book is finished, the reader is ready for any calculations that could be encountered at well control school. It is a great tool for rig crew members who are afraid of calculations or have not done any math since school. I found it easy to follow with clear explanations and it flowed from topic to topic. A definite addition to the rig crews training toolbox. Malcolm Lodge (at the time of writing Technical Director of the Well Control Institute)