In order to get admission in IIT Patna you have to appear for JEE Advanced exam.

First, you have to quailify for JEE Main exam in order to get eligible for JEE Advanced. You should be among the top 2,24,000 (including all categories) in Paper-1 of JEE (Main)-2018.

JEE Advanced maximum are not defined

 Maximum Marks vary every year like below:

 2017- 366

2016- 372

2015 - 504

2014 - 360

So, it is difficult to predict marks as exam pattern and marks change every year but you should score more than 50% marks to get good branch in Top IITs.

Good luck!!