This document discusses measures of central tendency, which summarize a data set with a single value representing the center or typical value. There are three main types of measures: the arithmetic mean, which is the sum of all values divided by the number of values; the median, which is the middle value when data is ordered from lowest to highest; and the mode, which is the most frequently occurring value. The document provides formulas for calculating each of these measures and explains their properties and uses for summarizing and comparing data sets.