The average of a group of numbers is found by adding all the data values together and dividing by the number of values in the group. Another word for the average is the arithmetic mean.
Suppose a student has made the following test scores: 95, 88, 75, 93 and 90. To find the average, first add the five scores together. The sum is 441. Next divide 441 by 5 to get the average, which is 88.2.
Though less commonly used than the arithmetic mean, other types of averages are sometimes calculated. Two such averages are the median, which involves finding the middle number of a set of values arranged in ascending order, and the mode, which is the value which occurs most often in a list.