1. The problem statement, all variables and given/known data This is a problem my lecturer did in class but I'm a bit confused. We have 2 large primes p=137 and q=131, choose e = 3 n = pq = 137.131 = 17947 (p-1)(q-1) = 136.130 = 17680 Compute d = e-1 mod (p-1)(q-1) = 3-1 mod 17680 = 11787. This is where I'm confused. How did he get d=11787? 2. Relevant equations 3. The attempt at a solution I think I'm supposed to use the Euclidean algorithm to find d, but he didn't show how.