Mean, Median, Mode and Range

Four quantities, four different operations. The mean is the total divided by the count; the median is the middle value once sorted (average the middle two if the count is even); the mode is the most frequent value; the range is largest minus smallest.

Sort the list before touching median or range. Contest sets are deliberately given out of order and often contain a repeat you will miss if you do not.

When a question combines them — "the range minus the mode" — compute each separately and subtract at the very end.