How do you actually get a number like that? What are the computations, simplified? Is it a coincidence that 1280 = 2⁷ * 10? (I mean, it makes me wonder if it isn't basically a result of using some sort of a decision tree splitting some set by 2 or something, and 10 is perhaps just some hard-coded into the model assumption — which it most probably isn't, of course, I'm just wondering: what is that number?)