Between Shangri-La and Xanadu there is a mountain of granite (density+1.60×10^2lb/ft^3). It is 1.00mi^3 in volume. Fate has decreed that a certaain family of birds send one of their flock once in every on hundred yeaers (1.00×10^2) to sharpen its beak by rubbing it on the mountain. In this process one-tenth of a milligram (1.00×10^-1mg) of the mountain is worn away each time.
