$N$ is a 50 digit number. All the digits except the 26th from the right are 1. If $N$ is divisible by 13, then the unknown digit is (A) 1 (B) 3 (C) 7 (D) 9
$N$ is a 50 digit number. All the digits except the 26th from the right are 1. If $N$ is divisible by 13, then the unknown digit is\\
(A) 1\\
(B) 3\\
(C) 7\\
(D) 9