Dear Usha, am sure you are aware of the fact that AIIMS has its own entrance examination for admission into its MBBS course and NEET UG exam has got nothing to do with AIIMS. Now thats settled, I also want to remind you that AIIMS has negative marking. At AIIMS marks are calculated through the cumulative percentile of both the slots. And most of the times, the ranking depends upon the difficulty of the exam and the no. of students who attended the exam. If the exam is tough, the cut off marks will be less and in such case even a slight lesser score can get you a better seat. And vice versa. As we cannot predict the difficulty of theexam and the no. of candidates appearing for the exam, it gets difficult to answer your question. But based on the previous trend at AIIMS, a score of 150+ can help you get a seat. Now if you ask me how to get to 150+, I would ssuggest, dont answer the questions based on assumptions. Negative marking can kill your scope. Hope this helps!