So dimensional analysis is seen as a fail-proof process that allows you to convert from one unit to another. You design the problems to begin with your given amount and to finish with the end amount of your unknown. Now just follow units to ensure the unwanted units are canceled out. In the same way that we did, metric prefix conversions where we line things up on opposite levels to help them cancel out, we're going to take that and apply it here to the dimensional analysis. Now the strategy is many conversion problems will utilize your given amount and conversion factors, and you're going to use those together to help isolate your end amount. So if we take a look here in this general format, let's say we're given 32 inches, so 32 inches is our given amount, and they're asking us to identify how many centimeters this equals. So centimeters is our end amount, what we're looking for. The conversion factor is a way of bridging these two ideas together. It's used to convert our given amount into our end amount. Now, to go from inches to centimeters means that we have to use a conversion factor that relates inches to centimeters. When we talked about conversion factors, we said that 1 inch is equal to 2.54 centimeters. I put inches here on the bottom so that they can cancel out with these inches up here on top. So you always want them on opposite levels. Doing that helps me isolate my end amount unit, which is centimeters. So then I would just multiply 32 times 2.54. Initially, I'll get 81.28 centimeters. But remember, when you're multiplying numbers together, your answer is the least number of significant figures. 32 has 2 significant figures in it. Because, remember, when you don't have a decimal point, you move from right to left. You start counting once you get to your first non-zero number and count all the way through. So this has 2 significant figures. When you have a decimal point, you go the opposite way. Our first non-zero number is this 2. You start counting here, you go all the way through. So we have 3 significant figures. So you go with the least number of significant figures, which would be 2. So this would round to 81 centimeters as our end amount. But let's say we had to do a type of dimensional analysis with way more steps. What do we do then? Well, let's say here we're given 115 minutes. So that is our given amount, and we have to get to years. Years would be our end amount. To connect given to end, we have to utilize conversion factors. I need to cancel out minutes, so I'll put minutes here on the bottom. We know that 1 hour has 60 minutes, and here, this will represent our first conversion factor. Minutes would cancel out. Now I have hours. We know that hours and days are connected. We know that one day has 24 hours. This would be my second conversion factor. Hours cancel out. Now I have days. And then finally, we know that days to years can be connected as well. We put days on the bottom, so they can cancel out with the days on top, and we know that 1 year has approximately 365 days. This is my third conversion factor. So days cancel out, and now I'm left with years. So what we're going to have here is 115 on top multiplying with a bunch of ones, which doesn't change anything, but on the bottom, we have multiplying 60, 24, and 365. Now it's incredibly important you know how to plug this into your calculator. My suggestion when you have multiple things on the bottom multiplying is to just multiply them all together and get that total. When we multiply 60 times 24 times 365, the total is 525,600, and we still have the 115 on top. When we divide 115 by that total, we're going to get 2.19×10-4. We're going to say here that the number of significant figures within our final answer is based on our given information. Now our only given information was the 115. These other numbers were the ones who supplied those numbers were not given to us in any way. So we can't use them to determine the number of significant figures. So again, it's all based on the information that's presented. Look at those numbers presented to you and use those to determine the number of significant figures in your final answer. 115 has no decimal point, so we move from right to left. It has in it 3 significant figures. So our answer should have 3 significant figures, which it does. So 2.19×10-4 years would be our answer here. So everything we've learned up to this point, we're going to use in some way when it comes to dimensional analysis. And remember, our conversion factors are incredibly important because they're a way of connecting our given amount to our end amount. The whole point is to cancel out units and isolate the unit that you're looking for at the end. Now that we've done these example questions, let's move on in our discussion of dimensional analysis.