We've been told the flag weight formula above 500 has an asymptote of 750. What exactly is the formula being used though?
I'm not sure the exact formula is particularly helpful, but the usual increase (10, 5, whatever) is multiplied by the exponent (of 10) of some negative number, calculated as the difference between your current weight and 500, along with some scaling factor. Such that at 500 you get full points (10^0 == 1), with that dropping fairly swiftly after that.
There is nothing particularly scientific about that, other than it gives the shape we were looking for. I can recall that it would take 1072 correct flags with none incorrect to get to something like 749.5. But getting 700+ is sooner (you flagging-crazy fiends know who you are!).
"How much to reach x" is probably unanswerable except with "from y, assuming no flags get bounced". Re % (comments); that isn't something we can directly report at the moment.
Since computers do lots of rounding, for all I know it might be possible to hit 750.00; but there is a hard max - even if the maths goes wobbly through rounding error, you cannot exceed 750.
It is not super-linear, it is asymptotic
The formula is.. well, to be a true asymptote, it must use something like TAN() or an inverted (1/x) series. Plug your own numbers and you can't go far from the truth.
You will never reach 750, for that is the definition of Asymptote
Except.. when it is not and asymptote. See here: http://meta.stackexchange.com/questions/84300/flag-weight-750-reached/88856#88856 It appears flag weight ALWAYS goes up by at least 0.1, right up to 750.