Hey I was just wondering if you know the height of the atmosphere, and the pressure that atmosphere creates on the Earth (1 atmosphere), then how would you approach calculating the number of molecules in the atmosphere? I was thinking of using the PV=NKT formula, where K is boltzmann's constant. I'm not sure if I can do this, but this is what I did. The only information I needed to calculate N was the Volume. So because I knew the height I simply calculated the volume of the Earth plus atmosphere and the volume of the Earth. Then I subtracted the volume of the Earth from the volume of the Earth plus the atmosphere. I get a value of an order of magnitude 10^44 molecule. By the way the Temperature is 0 degrees celsius. Can anyone tell me if what I did was ok or if what I did was wrong?