Sir how should i approach quants section as i am new to it(didn't touched maths after 10th)

Hi Rohit, There is nothing much to panic. You need to start with Basic Concepts across all Chapters: Go through all the chapters listed in CAT Syllabus. Then start with Easy Chapters like Percentages, Profit n Loss, etc. first. In every chapter complete the Basics, Formulae & Level 1 questions. Then you can get into tougher Chapters like Probability, P&C, etc. Once you complete all Level-1 questions Practise Level-2.
Then you can attempt Sectional tests and Mock tests. Mock tests help you to get familiarized to the pattern of the exam. They help you in getting used to the activity of sitting in one place for hours and attempting the test. Remember you need to be Smart while tackling this section. Employing logical approach, along with important shortcuts, tricks, and formulae will ensure that you solve the problems in a quick & efficient way. Speed also plays a crucial role in performing well in this section. If you take too much time in solving a question, then you will never be able to clear the cut-offs. The more you practice, the faster you become at solving questions.
You can increase your calculation speed by, learning/memorizing the following things:
Tables from 1 to 30, Squares of numbers 1 to 30, Cubes of numbers 1 to 30,
Values of fractions from 1/2 to 1/15, Factorial values from 1! To 8!, Common square root values.