Some colleges ​have mentioned valid IIT mains ranking, so what is the rank or score that they are looking for?? If you could just give me a rough idea of it.

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some college check for valid iit jee main rank , on the basis of that your admission will take place ,

it will depend on college to college that how much rank they will accept … based on your valid and genuine rank you will apply to particular college , and get admission .

hope this will clear your doubt 

good luck...