In this section, we practice calculating the median and mode of a data set. For example, we determine the median and mode from given frequency tables. The median is the middle number in a set of data after the data have been arranged in order. To calculate the median in a set of data (if there is an even number of data values), you add the two middle and then divide the sum by two. The mode is the most frequently occurring number in a set of data. If no number is repeated in a set of data, then there is no mode.