How to Calculate Sums and Averages in Google Sheets
You can use the SUM function to calculate totals in your spreadsheets.
There are two ways to insert a function. If you know the proper syntax, you can just type it in the cell as part of a formula. You can also select a function from a menu to insert it.
A new formula is started in the selected cell, using the SUM function. Now, we just need to enter the cell range we want to use by typing it in, or selecting the range on the sheet.