A range of cells can be easily added using the AutoSum button on the Standard toolbar. AutoSum suggests the range to sum, although this range can be changed if it's incorrect. AutoSum looks at all of the data that is consecutively entered, and when it sees an empty cell , that is where the AutoSum stops. Subtotals can be calculated for data ranges using the Tools menu and the Subtotals dialog box. This dialog box lets you select where the subtotals occur, as well as the function type.
Calculate Totals with AutoSum
Calculate with Extended AutoSum
Calculate Subtotals and Totals