 So how many moles are in 26.3 grams of carbon dioxide and how many atoms? So let's figure out how many moles there are first. So the first thing you're going to need to do is figure out the molecular weight of carbon dioxide. So carbon is 12.01 AMU and oxygen is 16.00 AMU. And you're going to time step by 2 and then add those two numbers together. So you're going to get 32 plus 12.1, which is 44.01. Hopefully know by now is that when you get this number, you can directly convert this to the molar mass. So what does that mean, the molar mass? That means how much does one mole of the substance work? So in fact it's going to be the same number but with different units here. So this is the molecular weight. The molar mass is going to be 44.01, but it's the same number with different units. So that really helps us in this first problem here because it will be a direct conversion for grams to moles. So moles, the symbol for that is N, so let's look for the N of CO2 that we've got. So all we've got to do is put 26.3 grams CO2 multiplied by what we've got this, which is essentially a conversion factor between grams and moles. So what we can do is say, well, 44.01 grams of CO2 is one mole of CO2. And then what happens is grams of CO2 can cancel out here and here. And then you just take this number, divide it by that number. You're going to want to go to three significant figures because that's the number that's given in the problem. So it's going to be 0.5. And from there, let's try to get the number of atoms, we shouldn't say atoms, molecules. CO2 is again the number of molecules equal well. We've got this moles here, okay? So, and we know one other thing. Can I talk in the race of this stuff here? What we know is Avogadro's number is basically going to be molecules. What we're going to do is we've got this moles here, which is a conversion factor. One mole of CO2 equals 6.022 and 10 to the 23rd molecules cancel out. And we just multiply. And again, you're going to want to take this to three significant figures.