Let's say you want to find the average number of days to complete a tasks by different employees. Or, you want to calculate the average temperature on a particular day over a 10year time span. There are several ways to calculate the average of a group of numbers.
The AVERAGE function measures central tendency, which is the location of the center of a group of numbers in a statistical distribution. The three most common measures of central tendency are:

Average This is the arithmetic mean, and is calculated by adding a group of numbers and then dividing by the count of those numbers. For example, the average of 2, 3, 3, 5, 7, and 10 is 30 divided by 6, which is 5.

Median The middle number of a group of numbers. Half the numbers have values that are greater than the median, and half the numbers have values that are less than the median. For example, the median of 2, 3, 3, 5, 7, and 10 is 4.

Mode The most frequently occurring number in a group of numbers. For example, the mode of 2, 3, 3, 5, 7, and 10 is 3.
For a symmetrical distribution of a group of numbers, these three measures of central tendency are all the same. In a skewed distribution of a group of numbers, they can be different.
Do the following:

Click a cell below, or to the right, of the numbers for which you want to find the average.

On the Home tab, in the Editing group, click the arrow next to AutoSum , click Average, and then press Enter.
To do this task, use the AVERAGE function. Copy the table below to a blank worksheet.
Formula 
Description (Result) 
=AVERAGE(A2:A7) 
Averages all of numbers in list above (9.5) 
=AVERAGE(A2:A4,A7) 
Averages the top three and the last number in the list (7.5) 
=AVERAGEIF(A2:A7, "<>0") 
Averages the numbers in the list except those that contain zero, such as cell A6 (11.4) 
To do this task, use the SUMPRODUCT and SUM functions. vThis example calculates the average price paid for a unit across three purchases, where each purchase is for a different number of units at a different price per unit.
Copy the table below to a blank worksheet.


To do this task, use the AVERAGE and IF functions. Copy the table below, and keep in mind that this example may be easier to understand if you copy it to a blank worksheet.
Formula 
Description (Result) 
=AVERAGEIF(A2:A7, "<>0") 
Averages the numbers in the list except those that contain zero, such as cell A6 (11.4) 
Need more help?
You can always ask an expert in the Excel Tech Community or get support in the Answers community.