You have a 10kg bag of sand. the mass of a grain of sand is about 10 to the -3 power gram. about how many grains of sand are in the bag of sand

10 kg* (1000 g/ 1 kg)* (1 grain of sand/ 10^(-3) g)= 10^7 grains of sand.
(Note that the units cancel out so you get the answer)

The final answer is 10^7 grains of sand.

Hope this helps~