MadeEasy Test Series: Computer Networks - Sliding Window

Question

I'm getting 81, but the answer given is 80. Please verify and explain.

Answer 1

To find the minimum window size,

= Bandwidth * RTT / Packet size
= 4 * 10^6 * 0.02 * 2 / 2000
= 80

Comments

I am also getting 81

Efficiency of GBN is = N/1+2a

For continuously sending data, the efficiency has to be 100%

for that value of N must be 1+2a

which comes out to be 1+80 (as per above calculation)

So, why not 81 ?