First list the numbers in order from smallest to largest :
5, 8, 8, 10, 10, 10, 11, 12, 12, 14, 17, 17, 19, 20, 20, 21
Finding the median means to find the middle value when all the numbers are listed in order from smallest to largest like above. So, we would cross out a number from left to right starting on the outside in to find the median.
Because two numbers are in the middle (12 and 12) we have to add them together and divide them by two to find the single middle value of the set.
The median is 24.