***Purpose of this Book*** The purpose of this book is to supply lots of examples with details solution that helps the students to understand each example step wise easily and get rid of the College assignments phobia. It is sincerely hoped that this book will help and better equipped the higher secondary students to prepare and face the examinations with better confidence. I have endeavored to present the book in a lucid manner which will be easier to understand by all the engineering students. ***PREFACE*** It gives me great pleasure to present to you this book on A Textbook on "Partial Differentiation" of Engineering Mathematics presented specially for you. Many books have been written on Engineering Mathematics by different authors and teachers, but majority of the students find it difficult to fully understand the examples in these books. Also, the Teachers have faced many problems due to paucity of time and classroom workload. Sometimes the college teacher is not able to help their own student in solving many difficult questions in the class even though they wish to do so. Keeping in mind the need of the students, the author was inspired to write a suitable text book providing solutions to various examples of "Partial Differentiation." of Engineering Mathematics. It is hoped that this book will meet more than an adequately the needs of the students they are meant for. I have tried our level best to make this book error free.