Your category rank will be displayed in your result.There are two columns in the result when you check it online.So, check your JEE MAIN result again.There you will find your Category rank.But i want to inform you that due to your poor rank in JEE MAIN you will not get any NIT or IIIT even by using your category rank.You can only get a seat in NIT of you belongs to northeast and then using your domicile for your home state NITs.
All the best.

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