Nisha, if you are referring to the MAT Composite Score, then you can calculate your percentage as follows:--

(Your score or Marks/ Total Marks) * 100

Now, in case of MAT, the total marks is equal to 800, so in your case, the formula comes out to be  (498.5/800) * 100

which comes out to be equal to 62.3125 percentage.

Now, to be honest, you would not be able to get the best colleges as your score and percentage is quite average but still you have chances in these decent colleges based on your percentage and the previous years trends (although the chances of a call also depend on your graduation credentials and your category status) :--

ACCURATE INSTITUTE OF ADVANCED MANAGEMENT, GREATER NOIDA

ACCURATE INSTITUTE OF MANAGEMENT AND TECHNOLOGY, GREATER NOIDA

IFIM BUSINESS SCHOOL, BANGALORE

COIMBATORE INSTITUTE OF MANAGEMENT AND TECHNOLOGY, COIMBATORE

SRM BUSINESS SCHOOL, LUCKNOW

ANSAL UNIVERSITY, GURGAON

If you want to know about the colleges which you may get based on your scores and previous years trends, you can visit this link

https://bschool.careers360.com/pathfinder/mat