Definition of Mean, Median & Mode

By Amy S. Jorgensen

Whether you are a math student, survey taker, statistician or researcher, you are going to need to calculate the average of multiple numbers from time to time. But finding the average is not always straightforward. In mathematics and statistics, averages can be found in three ways -- mean, median and mode.

Calculating the Mean

When you think of averaging, you are most likely to think of finding the mean. You add all of the numbers in the set and divide by how many numbers are in the list. For example, suppose you have the numbers 3, 7, 10 and 16. Add them up to get 36. Divide that number by 4 to get the average: 9.

Median: Think Middle

To determine the median, the list of numbers should be arranged in order from lowest to highest. The number in the middle, or the average of the two middle numbers, is the median. For example, if you have the numbers 1, 3, 5 and 7, the middle numbers are 3 and 5, so the median is 4.

Understanding the Mode

Mode refers to the number in a list that occurs most often. For example, in the group 12, 12, 16, 16, 16, 25 and 36, the number 16 is the mode.

Putting It All Together

If you have the numbers 125, 65, 40, 210 and 65, the average would be 101, or the total of all five numbers (505) divided by the number of data points (five). The median and mode methods, however, would produce different answers than the mean. For both, the average would be 65.