Which measure indicates the number that appears most frequently in a data set?

The mode is defined as the measure that represents the number which occurs most frequently within a data set. It is particularly useful in situations where the most common item or value is of interest. For example, in a data set of exam scores where the score of 85 appears most frequently among the students, 85 would be considered the mode.

The mean, or average, is calculated by summing all values in a data set and dividing by the number of values, which does not specifically indicate frequency. The median, which identifies the middle value when a data set is arranged in ascending or descending order, focuses on central tendency but not on frequency. Variation refers to how spread out the numbers in a data set are, which again is unrelated to identifying the most frequent number. Therefore, the mode is the correct measure for indicating the frequency of a number in a data set.