hello karthik,

the rank of 1000 and below can be obtained if you get a percentile of about 99.5 above. as the new system of marking is based on the number of students appeared for a session of exam and the difficulty level of the exam question paper of that session. so the percentile does not depend on the actual basis of marks. it vary independently of the marks obtained. if someone obtained 250 in one session but that session was comparatively simple to that of other session were a student could score only 150. the percentile would be more for the second student if the perfomance of the students of that session has an average below his score.

hope you understood

all the best