Hey Tejas!

There is a trend of reservation for only calculating the rank. It has nothing to do with the marks you scored.  You might have scored marks between 38-47.You can convert your JEE mains percentage to marks here:

Hi there,
Hope you are doing well.
With 70.4 percentile score in JEE Mains April, your rank would be around 2,80,000- 3,00,000.
and your OBC Rank would be around 90,000-95,000.
Converting into marks, your marks would be between 45-47 out of 360.
Hope it would help.
Thank You.