2) by direct division , we can see n leaves a remainder of 6 when divided by 8.
so n≡6mod8
so we have n2≡4mod8
hence proved
Hey guys , hope you are not too bored with maths . I found some good questions which I think don’t require pen and paper , yet are interesting . So please try ---
1 > If xy = 281 . 378 . 534 ( x + y ) , then find the number of integral solutions .
2 > If n = 640640640646 , then prove that n2 will leave a remainder 4 when divided by 8 .
3 > If p is a prime number , then prove that 1p-1 + 2p-1 + 3 p-1 ...........( p -1 )p-1 + 1 = 0 ( mod p )
2) by direct division , we can see n leaves a remainder of 6 when divided by 8.
so n≡6mod8
so we have n2≡4mod8
hence proved
http://targetiit.com/iit-jee-forum/posts/try-doing-these-12665.html
this is the other one-----can anyone expalin ans given by sawmya der