 When people think about computers and data, a lot of times they think about things like machine learning and these artificial intelligence algorithms that do these incredibly complicated things. But it turns out that the vast majority of tasks that we need to do with data are simple arithmetic addition and subtraction multiplication and division. And these are really easy to do in Google Sheets with formulas. But one thing we need to get started with is cell references. So when you're writing a formula, you need to have Google Sheets refer to the right cell. And you can do this with what are either called relative references or absolute references. And I'll demonstrate both. We'll begin with relative references. What I have here is a list of the numbers 1 through 10. And I want to take each of those numbers and I want to multiply it times 2. And I'm going to start by writing a formula. All I do is I type equals. That tells Google Sheets I'm going to write a formula. And then I click on the cell I want to multiply. It's 1 over to the left. And to multiply it times 2, I do asterisk 2. Great. And when I do that, you can see a preview of what these answers are going to be. I just hit it and there's a 2. If you want to see again what's going on here, just double click on this cell. And it will highlight the cell it's referring to. And you see the color here is orange and it matches here. If you have more than one cell reference, it'll do them in different colors. But you can see that there's a formula there. And then I'm going to click on that one and I'm going to drag it down. And what it's going to do is it's going to maintain the relative reference. And it's going to say at each step, take the cell that is 1 over to the left and multiply it times 2. If you want to see what all the formulas look like, you can do control tilde where the tilde on the US keyboard is above the tab. And that shows you all the formulas. And you see it goes to A3, to A4, to A5, so on down to A12 and multiply times 12. That's a relative reference because all it says is go 1 to the left. It doesn't say go to column A, although it has an A written here, but it just is interpreted as the next one to the left. Now there's other ways to do it. You don't have to refer just to the left. Let me turn off the view formulas. You may want to do a running total, in which case we do a combination of things. First I'm going to write a formula that says copy this one right here. That's the simplest possible formula. And then for each subsequent formula I'm going to say take the number that's right above and to that add the number that's to the left. So 1 above and add 1 to the left. And if I take that and drag it down, you'll see that in each point it's taking the number that's immediately above and the number that's immediately to the left and adding them up. And I get a running total of, by the time I get to the bottom here, 110. That actually is a useful thing to do if you are keeping track, say for instance, of invoices and you need to know the total expenditures doing this running total is actually how you would do it and relative references will be useful for that one. On the other hand, sometimes you say don't just go 1 to the left or 1 above, but you need to tell it to refer to a specific column or a specific row even when you're moving things around. That's where you get the idea of an absolute reference. Now I'm going to multiply numbers in this little table and I'll show you really how not to do it. We'll start by saying I'm going to type in equals to say so formula we'll take 1 to the left and I'll type in asterisk to multiply and I'll do it 1 to the top. Okay, 1 times 2 is easy, but watch what happens. If I drag that down, it's not going to do 5 times 2 here. It's doing 5 times 6 and if I drag that all to the right, then I end up with some really big numbers instead of this should be 30 down here instead of 3 million. And so that's not what we want to do. I'm going to back that up. Instead, I need to tell it that when it goes to the left, it needs to always go to column E. And when it goes to the top, it needs to always go to row 2. But even though it always goes to column E, it will sometimes need to go to this number or this number or this number depending on the row it's in. So we're going to do a combination of relative and absolute references. And the way to tell it to always go to one particular column in particular row is to use a dollar sign on the US keyboard that's above the 4. And that says always go to E although it can adjust the row. And over here it says you can adjust the column but always go to row number 2. And when I do that, watch what happens. I can drag that and now it works the way I want to. So if I click on this one, you can see it's multiplying that number and that number. If I click on this one, it's doing that number and that number. And if I do this cell, it's going the 6 times 5, which is 30. And so that's one way to do it. Now, by the way, there is a more sophisticated way of using something called an array formula here, but that's a special circumstance and I'm not going to get into that. And there's one other situation where you may want to use absolute references on both dimensions. Now, what I'm going to do is I'm going to recreate this table here by simply saying equals and I'll come up here and I'm going to copy all those values. These are relative references, by the way. And there we go. So I've got them all there, but I want to multiply each of these numbers times 10, which means it always has to go to exactly this cell, which is E8. And so what I need to do is I click on this formula here and I write an asterisk to do multiplication. I'm going to click on this cell, E8, but then I'm going to put a dollar sign before the E and a dollar sign before the 8. And then when I drag it down, it will always refer to that specific cell when doing the multiplication. So for instance, if I click right here, you can see it's taking that number, multiplying it times that. Here it's doing the relative reference up to here, but the absolute reference to this cell and the same thing here, relative reference to this one, but always referring to this one back. And so that's the combination of absolute and relative references. The way that you combine them gives you more flexibility in how you create your formulas and more power in how you set up your analyses.