p The importance of Working with Numbers has increased tremendously in all Aptitude based tests in the last few years. In CAT exam the number of questions asked have outgrown to 25. Further Number System is the stepping stone for whole of the Quant Data Sufficiency and Data Interpretation. The book Koncepts of Numbers captures Number System like never before. The book is an 100 original work by the author and contain some new copyrighted formula not in public domain at present. With more than 1300 solved questions divided into 10 different chapters it strengthens the basics and then further moves on to 5 difficulty levels of problems Concept Applicator CA Concept Builder CB Concept Cracker CC Concept Deviator CD Data Sufficiency DS. The book has a 360 degree approach towards solving problems and having 20 of the total questions on Data Sufficiency. Students appearing for competitive exams like CAT GMAT XAT IIFT MAT etc. would find it extremely student friendly. It clears the ambigousne