 Let's learn the rules now for addition when dealing with significant figures. So say we were given these three volume measurements, so volume 1, 37.68 mils, volume 2, 6.71, 862 mils, and volume 3, 108.428 mils. So we could probably by now figure out how many sig figs each one of these have. So let's just do that for fun. So this first one, V1, if we counted them, maybe 1, 2, 3, 4, of course, the four sig figs. So let's put a little column, V2 here, right? So these ones are pretty easy, I guess, because there's no zeros, I guess the last one has one zero involved, but 1, 2, 3, 4, 5, 6. And the last one, 108, it's got that one captive zero, but remember, of course, captive zeros are always significant, so 1, 2, 3, 4, 5, 6. Okay, so we did that, but we don't have to really use that for doing this addition of volume. So what's happened here, why do we have all these different significant figures? It's because we've used different measuring devices to get these particular measurements. So one of them measured very precisely, the one that measured V2 all the way down to this fifth decimal place, but the one that measured V1 wasn't very precise, it only went down to the second decimal place. But anyways, when we're adding, we can only, again, use the measurement that's the least precise. If we start using more precise measurements, measurements with higher decimal points, when we do that, we start to tell lies, if you will, not really tell the truth about how precise our measurement really was, our overall measure. So let's go ahead and add these things together. So really what you're going to do is go to the least precise one. So the one with not really the least significant figures, but it's going to be the least numbers after the decimal place. So if you see, this one has three numbers after the decimal place. So let's make another column, numbers after decimal. So this one's got two, this one's got one, two, three, four, five, and this one's got one, two, three. So that's the number you're really looking at. And in fact, when you add these up, the final number you're going to get is going to only have two numbers after the decimal place. So let's just go ahead and do it on our calculator. So just add these things up, 37.68 plus 6.71862 plus 108.428. So my calculator gives me this number, 152.82662. So and then, of course, we want to put metals on there because if we've got units on our number, then it's meaningless if we don't have units in our final answer. But anyways, that's not the right final answer. This is incorrect. If you wrote that on the exam, you'd probably get something off on it, especially if it was a sig fig problem, which this one is. Anyways, remember what you're going to do is not really so much worry about the number of sig figs, but you're going to worry when you're adding and subtracting how many numbers after the decimal. So this is for adding and subtracting, upline and dividing in a second. So this is incorrect. We've got to go to 2 after the decimal. So our answer would be 152.8 is higher than 5, so we've got to round up, right? So 8, 3. So if you wrote all of these, you'd be saying you've got 1, 2, 3, 4. And that's actually reporting to, this is something you want to remember for actually all of the things that you do in general chemistry, or introductory, or next in chemistry, or whatever class you're in, this is associated with it. If you're reporting more precise things, you're actually telling us.