The mean is the average. You do the average of a set of numbers by adding all of the numbers together and then dividing the sum by how many numbers there were.
The median is the middle number. You find the median by putting all of the numbers in order (including the repeated numbers) and taking numbers off the ends until you have one or two numbers in the middle. If you have one left, that is the median. If you have two left, then the number directly in between the numbers is the median.
The mode is the most repeated number. The number that appears most in the set is the mode.
EXAMPLE:
8, 2, 1,8,7, 6
The average is
5.3333333333333333333333333333333333333333333333333333334
The median is 6.5
The mode is 8