Question

Find gcd $(2^{100}-1,2^{120}-1)$.

• A. $2^{20}-1$
• B. $2^{40}-1$
• C. $2^{60}-1$
• D. $2^{10}-1$

Answer 1

The correct option is A $2^{20}-1$

The GCD of $A^x-1$ & $A^y-1$ is given by $A^{(GCDofx,y)}-1$. Hence, the required answer would be $2^{20}-1$.