 Okay, let's go ahead and do the second problem you picked. When we look at it, this problem, it's asking us to convert the density of platinum from grams per cubic centimeter to pounds per cubic inch. And when you do this problem, it's very easy to make a very common mistake. So I like to present it this way for the first time, at least for the first time that y'all see it. So just like any or any of these other problems that we've been doing, it's a multiple conversion problem. So the going from grams to pounds is straightforward. It's what we've been doing this entire time. So taking grams, canceling it, and getting it into kilograms, using the conversion factor, one kilogram equals a thousand grams, and then taking that to pounds using the next conversion factor. It's this next part going from cubic centimeters to cubic inches that often trips up, especially introductory chemistry students. So when you do this part of the calculation, you not only need to cube the units, the centimeters and the inches, but you also have to cube the numbers. So in this case, it's the 2.54 and the one inch, or the one. And if you don't do that, you get a weird answer. So the way I usually like to present it the first time is the way it's presented at the top, where you just cancel out centimeters, centimeters and centimeters. That's three times you're canceling out centimeters, and that would be equivalent to centimeters cubed. It really emphasizes the fact that that 2.54 is a conversion factor for the one inch. So you need it each time. So oftentimes, students will only use the 2.54 one time. And if you did that, you'd get a different answer. It would be, I guess, 0.120 pounds per cubic inch. And of course, as you see, that's not the correct answer. When you get better at this, you can do it the way that I presented it down here, where you see I've taken the entire conversion factor and cubed it. Because that's what your cubing is, that conversion factor when you're doing this. So you see, when you do that, you get the same answer as your other method of doing it. Make sure you are doing it correctly and not getting that alternate answer. That is the incorrect one, the 0.120 answer. And also remember, you're correct significant figures. There's three significant figures in the given density. So you have to have three significant figures in your answer. Let me know if there's any issues with that one.