Hi sanika!
You can check the percentage in the jnvst Navodaya exam by login in at the official Navodaya vidyalaya samiti portal using your roll number and date of birth. Once the result is visible you can calculate the percentage manually by dividing the marks which (scored by you in total) by the total marks and multiply by 500.
Now talking about cutoff for SC category students, in recent years the expected qualifying range for class 6 admissions usually range between 60-68 marks out of 100 which is roughly 51% to 68%.
This means that your score of 51 out of 85 is at the lower end of the expected SC cut off. So it does not confirm your selection but you can hope for it as performance is in that range and it often falls within the qualifying bracket.
Hope it helps!
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile