Dear student,

First of all you must mention the examination name. Now as per your profile, you are an engineering aspirant, so i can assume that you are asking about jee mains.

Now, if you want to score 99 percentile or above in jee mains then as per the marks vs percentile stats, you must secure atleast above 150 marks.
But with this much marks you cannot get a good nits or iiits.

For getting a good nits or iiits, you must secure above 99.8 percentile, and for that your score must be above 220.

Also check out the following marks vs percentile for jee mains 2020 :-
https://engineering.careers360.com/articles/jee-main-marks-vs-percentile/amp

Hello aspirant,

To score more than 99 percentile , one should attempt a minimum number of questions in the CAT exam. On an average, the correct attempts and score required for a 99 percentile is: Quantitative Aptitude (QA) - minimum 23 question out of 34. Data Interpretation and Logical Reasoning (DILR) - minimum 22 questions out of 34.

Hope it helps!