Everyone who uses Google Sheets on a regular basis should know how to do math on its interface, especially multiplication. I will show you a simple 3-step process for multiplying your columns.
Step #1: Select the Cell
First, you need to click the "Cell" where you want the result of the multiplication to appear. You should select the topmost cell of that column, as that will help you fill out the rest of your chart later.
Step #2: Multiply
There are two functions that you can put into the command box to multiply the two cells together
"=MULTIPLY(Cell1,Cell2)" and "=Cell1*Cell2"
In the first method, simply use the "=MULTIPLY()" function to multiply your cells together. Once you do that, simply hit enter, and the product should appear in the cell you selected in step #1.
Keep in mind that you must add the comma between the two coordinates. Otherwise, the function will not work.
Alternatively, in the case of the example shown above, you could multiply the cells together by typing "=B3*C3". That will have the same effect as the "=MULTIPLY()" function, but it can be used instead of that function.
Many people prefer this method because it feels more like you are using a calculator. As such, this technique comes more naturally to people.
Step #3: Click and Drag
Once you hit enter, you will be able to fill out the rest of the column automatically. Simply click and drag the topmost product cell from the top to bottom row.
The function will be applied to each new cell as you drag down the column. Not only that, but as you descend the column, the referenced cells follow, meaning that you will get accurate results for every row.
That is how you multiply columns in Google Sheets