64According to Douglas Giancoli’s Physics for Scientists and Engineers textbook, the mass of the Earth is 5.98 × 1024 kg, or 5.98 × 1027 grams. Dividing 2128 (the number of unique IPv6 addresses) by the Earth’s mass in grams yields the number of available IPv6 address per gram of Earth mass. Furthermore, if we assume a grain of sand has a mass of about 1 milligram, and that the Earth is modeled as a very large collection of sand grains (not quite the truth, but good enough for a dramatic illustration!), we arrive at 57 million IPv6 addresses per grain of sand on Earth.