Dear student,

The percentile score is the mark on which you have scored more than the other students taking that exam.

For example: If you scored 50 percentile marks that mean you scored marks above than 50% students, it does not mean that you have scored 50% marks in the exam (like if the exam is of 100 your score is 50).

Its doesn't matter that you scored 50 out of 100 or 80 out of 100, if other 50% students scored 80 out of 100 too, then the percentile score of you will be 50 only when you have 80+ marks.

Hope this helps you!