Click the cell where you want the total to appear
Type `=SUM(`
Select the column range you want to total
Type `)` and press Enter
Example: `=SUM(A:A)` to total the entire column A
Example: `=SUM(A1:A100)` to total cells A1 through A100
Use AutoSum by selecting the total cell and pressing `Alt` + `=` on Windows or `Command` + `Shift` + `T` on Mac
Press Enter to calculate the total