Excel 2013 knows that you’ll use some calculations more than others, and for this reason, on the Home tab you have a tool within reach to help you perform some common calculations. Specifically, the Sum tool in the Editing group gives you access to functions you might use often: Sum, Average, Count Numbers, Max, and Min. You can also display additional functions by choosing More Functions in the Sum tool list and use the Subtotal tool on the Data tab to subtotal values on your worksheet.
Click the cell in which you want to create the formula.
Type the equation you want Excel to perform, starting with the equal sign (=).
Press the Enter key.
Excel carries out the math and displays the ...