 Okay, so you picked a problem that incorporates a lot of the things that we've been talking about using conversion factors. Let's see what else. Scientific notation, your rounding rules, and significant figures. So this one incorporates a lot. The 3.3 pounds that the student has lost, we want to convert that into grams, so we know we need to just do a mass to mass conversion, so we just need a couple of conversion factors. The first one that you know is the 2.205 pounds is one kilogram, and the other one is one kilogram is a thousand grams. So just on the top I do it the kind of way we've been showing it, with the pounds being cancelled first, giving us kilograms, and then we cancel the kilograms with our second conversion, giving us grams. I mean the calculator actually gives us 14.96.5 grams, but if we look the original mass number only had two sig figs, so we've got to keep our significant figures the same. So we've got to put this into scientific notation at 1.5 times 10 to the third grams. So on the bottom line I actually showed you a little shortcut. If you look at the two conversion factors you see that both of them are equivalent to one kilogram, right? So that means that the other things are equivalent to each other, in other words the 2.205 pounds is equivalent to one thousand grams. So if you ever see this you can just quickly make your own little conversion factor there combining the two, and you don't have to do so much writing out to show your work. If that helps, let me know.