Operational Research (O.R) is the use of advanced analytical technique to improve decision making, because it brings sense to make the best use of available resources. Hence every O.R analyst must possess interpersonal skills and be able to work with management by providing quick solutions to the problems. Despite their theoretical knowledge in O.R-techniques, familiarity in computer software is also highly desirable to meet the timely requirements. This book focuses on the simplest method of solving Linear Programming Problem (LPP),Integer Programming Problem(IPP), Transportation Problem(TP) and Assignment Problem(AP) using Solver tool available in MS-Excel. Though several software are available exclusively for these solutions which require special attention and more time to understand and learn. This book guides not only young researchers and students at postgraduate level, who face difficulty in solving LPP, IPP, TP and AP problems manually but also managers of companies, who don't have sound mathematical background. Step-wise procedure explained in this book takes care of persons, who have only basic knowledge in computers. Three real time problems are solved and summarized.