Q.

The remainder when ((64)(64))(64) is divided by 7 is equal to          [2025]

1 3  
2 1  
3 6  
4 4  

Ans.

(2)

Let A=((64)(64))(64)=(64)642

       A=(1+63)642, let 642=n

Expanding by binomial

       A=(1+63)n=1+C1n(63)+C2n(63)2+...=1+63λ=1+7(9λ)

   When ((64)(64))(64) is divisible by 7 then remainder is 1.