Cool, thanks for the explanation and calculation. I may have missed this, but where does 7040691 come from?
1000000000 x 10 x 60 x 65535 / 2
48 x 2016 x 25 = 7040691
Here are where those numbers come from:
1000000000 x 10 x 60 is the expected number of hashes per block (per GH/s)
65535 / 2
48 x D is the probability of finding a block
2016 is the number of blocks per period
25 is the block reward