Everyone should know how to do basic addition in Google Sheets. I will show you how in just two quick and easy steps.
Step #1: "=SUM()"
First, you will click the cell that you want the sum to appear in. Then, you will use the function "=SUM(Cell1,Cell2)" in my case those two cells are B3 and C3. So my function will read as "=SUM(B3,C3)"
Alternatively, you could also use the function "=Cell1+Cell2" to add the cells together.
In this case, the function would read as "=B3+C3".
I personally prefer this function because it feels more natural than the "SUM" command.
Step #2: Click and Drag
Lastly, you can click and drag that cell all the way through the column. As you drag down the column, the variables will change to match the cells in that row. It is an easier technique than manually typing in the code a ton of times.