Dear please specify the question clearly.!

I guess you are talking about general exams like JEE MAINS/ADVANCE etc. For that I think it is next to impossible to find the reault of some random person. Reason is that evwn if you guess a correct roll number than you also require to know tbe Date of Birth of the candidate having that roll number. Since in a year there are 365 days and and the age can vary 2 years, so you require to make 730 guessses approximately with no surety that the DOB is within the range you thought.