If one grain of rise weights 2 mg, then 2^64 - 1 grains of rice weigh
about 36,000,000,000 metric tonnes (i.e., thirty six thousand million).
That's a crapload of rice! (Wolfram Alpha claims it's roughly 50% of the
total biomass on planet Earth.)
I guess the moral of the story is do NOT screw with exponential
functions. (!!)
