The mean of a series of numbers is the average - calculated by added all the numbers in the series and dividing the sum by the number of numbers in the series. Given the set of numbers {1,2,3,4,5},...
Middel so lets say you have a group of numbers such as this group below
18 , 20 , 34 , 15 , 78 , 100 , 12 , 46 , 89
You put those #s is order from smallest to largest like this
12 , 15 , 18 , 20 ,...
The word "mean" in math means the average of several numbers.
To get the average
1. add all the numbers together
2. divide the sum of the numbers by how many numders there were.
ex.
1....
18 is a number, not a word. And also, 18 is a composite number that is often used in problems. Numbers that are factors include 1,2,3,6,9,18. Multiples include 36, 72, and others.