The Mean or Arithmetic mean is not the center, neither is it the largest or smallest data value. On the contrary, it does have a value (not necessarily in the data themselves). So I would define the Mean or Arithmetic Mean as the sum of all the values in a given set of data divided by the number of data in the set. Suppose we have a data set 5, 8, 9 the Arithmetic mean is 5 + 8 + 9; we divided the result by the number of data which is 3 . Hence in the above data set our mean is 22/5 = 4.4