Hello keshav,
Percentile is not percentage. There is no exact number that could be called 80 percent out of this marks. Percentile is almost different for each year. To measure the exact number with 80 percentile, you have to look out your result, it varies every year depending upon the number of questions and the maximum marks gainer. It possible that you score 280 out of 300 but still your percentile is 25 because the rest of the 75 percent must have scored better than you. It changes year to year. I hope you have understood.
Good luck.
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile