 So let's try some examples. Firstly, 20.1 divided by 0.047. We put that into the calculator and we get 427.65957 etc. Now of the two numbers that we used in our calculation, 0.047 has the fewest sig figs. It has two. So our final answer must also be rounded to two sig figs. This gives us 430. Next, 47.2 minus 0.8359. We put it into the calculator and we get 46.3641. Now because this is a subtraction we're looking at decimal places and not sig figs. So the first number has one decimal place and the second has four. Hence our final answer must be rounded to one decimal place and that gives us 46.4. Alright next, 0.9814 times 24. We put that into the calculator and we get 23.5536. Of the two numbers that we used, 24 has the fewest sig figs. It has two. So our final answer must also be rounded to two sigs which gives us 24. Now does that seem a bit weird? We've multiplied 24 by something that's not one and yet we still ended up with 24. Well the reason is that we don't know the original 24 very accurately. It's not 24.00 for instance. So when we multiply it by a number that's very close to one it doesn't make enough of a difference for us to be able to see a change. Alright lastly we've got 10 liters plus 9.6 milliliters. Think about a full 10 liter bucket and a 10 mil measuring cylinder with 9.6 mils of water in it. Well we can't just add 10 liters to 9.6 mils. Why not? Well the units are different. We need to convert one of those values so that both of them have the same unit. I'm going to convert 9.6 mils to liters. Quick conversion shows us that it's 0.0096 liters. So then we have 10 plus 0.0096 which gives us 10.0096. But it's an addition so we're checking decimal places. Now the 10 liters has no decimal places so our final answer must also be rounded to no decimal places. And that makes it 10 liters. This is an example a little like the previous one where it seems like nothing has happened. Because the large volume here was much less accurately measured than the small volume, adding the small volume does not make a measurable difference. Imagine pouring the 9.6 mils into the 10 liter bucket. Would you see a measurable change in the level of the water? If however the 10 liters had been measured in a giant volumetric flask or on a balance and it was known to be 10.000 liters, then the extra 0.0096 liters would be measurable. Now let's do one final example. Say we have 10 measuring cylinders and each one contains 153 mils of water and we want to know what the total volume of water is. We're going to pour all of these into a single container. Calculation is 10 times 153 giving the calculator answer of 1,530 mils. But you might look at that and say well the 10 only has one sig fig so I should round that off to 2,000 mils. But think about it. The 10 refers to the number of measuring cylinders. Is there any doubt about how many measuring cylinders there are? Do you think if you measured more carefully you might find that there was actually 10.1 measuring cylinders? Of course not. The 10 figure here is what's known as accountable or an exact number. It in effect has infinite significant figures. It is known exactly. In consequence it does not affect the number of sig figs in your calculation. So here we use the sig figs in the volume measurement to determine our answer. And since there are three that means that our original, the original answer that the calculator gave, 1,530 mils is actually correct.