The MEAN or average is the most commonly used measure of valuation
data. However, it can lead to error in valuation analysis as it is
heavily influenced by very high and very low data. In a group of sales
data it is common to have one or two very high sales and/or very low
MEAN = (SUMX)/n
It is easily found with the following spreadsheet commands:
Excel: =AVERAGE(data cells)
In Libre Office Calc (a free spreadsheet, the same.