In any competitive exam, a part of the question paper definitely comes from here and most of the contestants can not do well in this part of the exam due to a lack of proper understanding. This book is so simple and nicely discussed that after reading it all the basics will be clear and you will do well in exams too. It is very important in our daily life so read the book now and keep yourself one step ahead of others. Good luck to you and best wishes for your future.