 It's my turn. Okay, so let's try this problem. This is the first problem from quiz two. How many sig figs are contained in the following numbers? Well, here's a list of those numbers and all we're going to do is look at those numbers and decide, right? Just put a number button. So if we look at this first number, 3.8 times 10 to the negative 3, what we find is we've got a lot of numbers here, but only two of them are significant, okay? So those two would be these two, 3 and 8. All of this stuff times 10 to the negative 3 that you don't have to worry about, okay? So in this case, you've only got the two significant figures. Remember, scientific notation, the point of putting it into scientific notation is to describe the amount of significant figures that you got. All of this stuff beyond the first two numbers here is insignificant business, okay? So let's apply that same rule to this thing, 5.20 times 10 squared. Remember, we just cover all that stuff up. This one's got a little bit extra rule in there because of that zero. If that zero is after the decimal place like it is, then it's significant, okay? So in this case, we've got 1, 2, 3 significant figures. Hopefully this one's a little easier for you, but again, it gives you another chance to review your zero rules. If zeros are before the first non-zero digits, then they're insignificant, okay? So in this case, this zero, this zero, this zero, they're all insignificant. Why is that? Because 2 is the first non-zero digit, okay? Does that make sense? Does that make sense? Yes. Okay, so insignificant, insignificant, insignificant. 1, 2, 3, 4, right? Watch this. Let's put this into scientific notation. Okay, let's put this number into scientific notation. If we get that, what would we do? We'd take this decimal place and move it behind that 2, right? 1, 2, 3, like that. So it's going to be 2.616 times 10 to the negative 1, 2, 3. Look, if we look at our scientific notation, how many significant figures does that tell us? Four, okay? So this has to have the same amount of significant figures as this, or there's different numbers, right? So remember, four significant digits. If you put them into scientific notation, you'll know it very easily every time. Well, this number is 24. Well, there's two significant digits. There's no zeros, no decimal place, no nothing. So it's pretty straightforward. 240, this one's a little tricky, okay? Because there's a zero at the end, but there's no decimal point after the zero, okay? Since there's no decimal point here, this implies that this figure here, or this zero here is insignificant, okay? So this one actually also has two significant digits. If I were to put 240 with the decimal place there, then that would be saying that this zero is now significant, so we would have three significant figures on that, okay? Does that make sense? Okay, the difference between those two numbers. And then this one, of course, 2.40. Again, if there's a zero after the decimal point like we have here, this is also significant, okay? So in this case, we've got one, two, three significant figures. Okay? If you want, we can...