 Okay, so this problem on the surface seems pretty straightforward but it's easy to get these types of problems incorrect because we often times forget to cancel out the appropriate number of units, the appropriate number of times, or we forget to multiply the numbers within the conversion factors by themselves when we have these squared or cubed units. So we have 435 acres to start out with and we've got the conversion factors from acres to square feet and miles to feet up there. So it seems straightforward like I said cancel out acres with acres to get square footage. But now we have units that are squared so we have to remember to do the conversion factor twice. So that's why I write it out explicitly and I like to do this with introductory chemistry students just to remind them that you have to divide by 5280, two times. So when we do that, that cancels out both of the feet or feet squared and then we multiply miles times miles and we get miles squared. So the answer is going to be 0.680 miles squared. So you want to remember that it's going to have three sig figs due to the fact that the number given by the problem has three sig figs. So you're going to have to put that zero at the end because that is significant. So if you look at the second line there, I've reduced the problem to squaring the conversion factor. So I want to emphasize that you have to square the entire conversion factor, not just the unit portion because sometimes we forget to square the one in the 5280 and if we solve this problem, forgetting to do that, we'll get an answer that is around 3588 square miles. And of course, if you really think about it, that doesn't make sense, but it's easy to mess up. So don't get too discouraged if you got that other answer. Just adjust your thinking and I think that it'll become clear when you do a couple more of these problems. Okay, hopefully that helps.