This book is intended for those who completed school studies and who had calculus course and trigonometry course in schools. If a student is particular in developing a software package containing programs to solve numerical problems, he/she should know the fundamental principles for numerical methods. This book also fulfills this need of a student in a way because it provides introductory formal as well as non formal methods. It provides details in worked-out examples so that this book will also be suitable for students who pursue online courses in introductory numerical analysis.