Mean, median and mode describe different characteristics of a data set. The mean is the sum of the values divided by the number of values. The median is the middle value when the data is sorted. If the number of values is even, the median is the average of the two middle values. The mode is any value that occurs most frequently in the set; there may be more than one mode. The average of a data set usually refers to the mean, though representative values such as median or mode are sometimes referred to as averages. Add an extra value to the list of data to find out how it affects these results. Generate a new set of random numbers by changing the random seed.