Why is Gulzar Peer Tuitorialas material considered the best for IIT and Olympiads? Even though it is whoopingly expensive?

My rank is 29k, General, should I opt for any state college cse branch or some Nits in which in which I am getting ECE , chemical, mechanics etc....

How is Ranquer Eduzone,comparing, Akash,Fitjee,Resonance,Naryana

Can class 9th students study syllabus classof 11th

Sum of series 2[n/2] ! [n/2]!/ n! [2Co-2C2+3C2....+[-1]^n[n+1]2Cn] where n is an even positive integer. Kindly provide solution of this question and how to generalise this. How do we know that which expansion will give this?

I m foreigner,How much mark i need to get into IIT??