Dear Student,

Greetings.

It is calculated as percentile for the scores of a particular student. The percentile score in a particular board, or at All India Level, of a candidate is calculated in this way: suppose, a candidate belongs to Board X (eks) clears his 12th Board Exam with a score 490 out of 500, then his % is 98, and his rank is 5th among a set of 20,0000 students. Then this particular student's position is above 199995 students, or the same numbers of students fall under him. In this case, the percentile score of this student will be 100 x (199995/200000), i.e., 99.99. 

In this way, we get this student's percentile score (99.99), and we know his board percentage, that is 98%. In the same way the percentile score of all candidates can be calculated.

I hope it is clear.

JEE Mains result is usually announced as:-

For example a person has scored 200 on 360 then the score is mentioned as 200/360.

Also the marks scored in different subjects are given differently. Percentile is also given many a times. 

If you still have any queries feel free to ask in the comment section down below. 

All the best.