Dear student,

For getting into nits you have to clear the exam called JEE MAINS. Jee mains is a national level exam and a prelims for jee advanced.
If you want to pursue your career from a good nit, then you have to clear the jee mains with a good rank and score.
For getting a nit your score should be above 99 percentile , that is you must secured atleast 150 marks. And for good and top nits your score should be above 99.5 percentile i.e, your marks should be more than 180.
And higher the better.

Check out the following link to know the marks vs percentile stats of jee Mains 202 :-
https://engineering.careers360.com/articles/jee-main-marks-vs-percentile

Also check out the following link to know more about jee mains 2021 :-
https://engineering.careers360.com/exams/jee-main