Also, the author did not spend two days. he spent 17 minutes and then did the math to calculate the block hash rate. > Doing one round of SHA-256 by hand took

Also, the author did not spend two days. he spent 17 minutes and then did the math to calculate the block hash rate. > Doing one round of SHA-256 by hand took me 16 minutes, 45 seconds. At this rate, hashing a full Bitcoin block (128 rounds)[3] would take 1.49 days, for a hash rate of 0.67 hashes per day