Mathematicians and researchers often have large sets of data collected on a certain problem, such as the household income of American families. To summarize the data, they often use the mean, median and mode.

## Mean

The mean is the average of all numbers in a data set. For example, in the data set {1,1,2,3,6,7,8}, add the total and divide by seven, the number of items in the data set. The calculation would show that the average is four.

## Mode

The mode is the most commonly occurring number in a data set. In the data set {1,1,2,3,6,7,8}, the mode would be one because it appears more than any other number.

## Median

The median is the middle number in the data set. For example, given the data set {1,1,2,3,6,7,8}, the median is three because there are an equal amount of numbers greater than three and less than three.