Mean is the average number in the data set.
To get the average we first add all the numbers.
After we add all these numbers we then divide by the number of numbers in the data set.
So we do 22+18+38+6+24+18 which is equal to 126 there are six numbers so we divide 126 by 6. This gives us a mean of 21.
ANOTHER EXAMPLE:
Another example of this is the data set (4,65,7,34,5)
We first add all the numbers and get 115 then we divide by 5 and get 23 as the mean.