Essential Idea Section 10.2: Measures of Central Tendency Situation Measures of Central tendency: Mean, Median, and Mode Mean. The number found by adding the data and then dividing by the number of values in the data set. Median. The middle number when the numbers in the data set are arranged in order of size. If there are two middle numbers (in the case of an even number of values in the data set), the median is the mean of these two middle numbers. Mode. The value that occurs most frequently. If no number occurs more than once, there is no mode. It is possible to have more than one mode.