The mean is average of all numbers, regardless how many. We are going to easily calculate it with the help of Excel.
Calculating a mean
Write all the numbers you want to know the mean of, and laid out in the same roll.
Click on any blank column and type in =AVERAGE(choose from first to the end ex. A1,A22).
Formula here is: =AVERAGE(A1:A14)
Note: The 85.35714 is the mean of all numbers.
See more AVERAGE function examples here.
Further reading: Rolling average Moving average Geometric average Weighted average