Quote from: elisacat on Today at 04:18:59 PM

Quote from: WanderingPhilospher on Today at 03:31:50 PM

for each range, do 2 to the power of the bit range. Example 2 ^64 = 18,446,744,073,709,551,616; now divide that by # of key/s. example; 2 ^ 64 / 1,000,000,000 (1 billion key/s) = 18,446,744,073 seconds = 307,445,734 minutes = 5,124,095 hours = 213,503 days = 584 years . I think that math is accurate. but basically 2^64 / 1000000000 / 86400 (seconds in a day) = 213,503 days / 365 (days in a year) = 584 years

So, if by some chance i knew the first 2 characters for puzzle number 64 then it becomes a 50 bit password hash problem right? in which case it would take roughly 100 days to solve if i understood your formula correctly

I calculate 834 days:

2^56 / 1000000000 / 86400 = 833.99

For each character you know, in your example, the first 2, so let's say the key is 81C3F8710B26AC39, and you know the first 2 characters are 81, then you would need to solve the last 14 characters which would be 2 ^56 (14 x 4)