Robert demonstrates how to quickly insert formulas into Excel. To create a sum, highlight your selected cells and press the sum key. Expand the formula by clicking on the fill handle. Double click on the fill handle to expand the formula. To sum vertical columns, highlight all the cells and click the sum button. Press and hold down the control key for another shortcut to work in accordance with the auto sum button. You can also select the average for the area. You can also select the area and write the formula. By pressing control + enter, Excel will automatically fill in the rest of the formula propagation.