Select the cell where you want the result
Type =SUM(
Click the first cell you want to add
Type a comma or colon if adding a range
Select the other cells or range
Close the parenthesis )
Press Enter
To add individual cells, use =A1+B1+C1
To add a range, use =SUM(A1:A10)
To add non-adjacent cells, use =SUM(A1,C1,E1)
To use AutoSum, select the cell below or beside the numbers
Click AutoSum on the Home tab
Press Enter to confirm the formula