The most simple Excel addition formula consists of the = sign, followed by a list of two or more numbers with the + operator in between them. This is shown in the spreadsheet on the right. The excel addition formula on the right calculates the sum of the three numbers 2, 7 and 1 and returns the result 10. 


As with all Excel formulas, instead of typing in the numbers directly, you can use references to cells containing numbers. The Excel addition formula in cell A1 of the spreadsheet on the right adds together the contents of cells B1, B2 and B3. Again, the formula returns the value 10. 

Instead of using the + operator Excel provides a builtin Sum Function that can be used to perform addition in Excel. This function is called by entering the following into an Excel cell:
where number1, [number2], etc. are one or more numbers (or references to cells containing numbers) that you want to add together. The Sum function is used in cell A1 of the spreadsheet on the right. In this example, the function is used to add together the three values in cells B1, B2 and B3, and therefore, returns the value 10. 

For more information and examples of the Sum function, see the Excel Sum Function page.