16. The number which represents the average value amongst a series of numbers (mean, mode, median).

The term "average" converts into the mathematical mean. Here are a series of numbers and their various summaries.

Numbers: 3, 5, 6, 8, 10, 12, 14, 18, 18, 18, 18, 20, 25

Mean: 13.5, sum of all the numbers above (175) divided by the number of numbers (13)

Mode: 18, the number with the greatest frequency.

Median: 14, the number in the middle.