The average, or mean, gives you a single number that represents a whole set of values. You find it by adding all the numbers and dividing by how many there are, which is useful for grades, prices, scores, and more.
What you'll need
- A calculator (optional)
Step by step
- List all the numbersWrite out every value you want to average, for example 4, 8, 15, and 9.
- Add them togetherSum all the values. In the example, 4 plus 8 plus 15 plus 9 gives a total of 36.
- Count how many values there areCount the numbers in your list. Here there are 4 values.
- Divide the total by the countDivide the sum by how many numbers you added. In the example, 36 divided by 4 gives an average of 9.
- Double-check the resultConfirm the average falls somewhere between your smallest and largest values, which it should for a correct calculation.
Handy tips
- Make sure you divide by the count of numbers, not by the largest value.
- For a weighted average, multiply each value by its weight before adding, then divide by the total of the weights.
- The average can be a decimal even when all your numbers are whole numbers.
FAQ
Is the average the same as the mean?
In everyday use, yes. The word average most often refers to the arithmetic mean, which is the sum divided by the count.
What is the difference between mean, median, and mode?
The mean is the sum divided by the count, the median is the middle value when sorted, and the mode is the value that appears most often.
Can one very large number change the average a lot?
Yes. A single outlier can pull the mean up or down significantly, which is why the median is sometimes used for skewed data.