The most basic Excel Average Formula consists of the = sign, followed a sum of two or more values, divided by the number of values in the group. A simple Excel average formula, which calculates the average of the three values 5, 10 and 15, is shown in cell A1 of the spreadsheet on the right. As expected, this formula returns the result 10. 

Instead of using the + and / operators, as shown above, you can use the builtin Average function to calculate an average 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 calculate the average of. Cell A1 the spreadsheet on the right shows an example of the Excel Average function, used to calculate the average of the three values in cells B1, B2 and B3. Again, the formula returns the value 10. 

Further information and examples of the Average function are provided on the Excel Average Function page.