Hello Himanshu,

Are you asking for top 20 percentile for NITs, IITs admission of ASHC? To calculate top 20 percentile for different class 12 boards, marks scored in five subjects is considered:

Physics,

Chemistry, Mathematics,

A language and Any subject other than the above four

Top 20 Percentile Cutoff for AHSEC ( Assam Higher Secondary Education Council) for Open Category is 360.

You can prefer the below given link for the further information.

https://engineering.careers360.com/articles/top-20-percentile-of-class-12-boards-for-nits-iiits-and-cftis

Good Luck!