# Percentage Error

## What is Percentage Error?

Now that you know how to estimate answers to problems, you are ready to learn about percentage error. The percentage error, is a percentage that tells
us how far an estimate if off the actual answer. It is calculated using the error (in numerical values) and the exact answer. It is a very good way of
identifying how exact your estimate was.
Calculating Percentage Error
To calculate the percentage error you need to fin the error (the difference between
your estimation and the exact answer) and the exact answer. On the right, you can see
the formula used for calculating the percentage error. The vertical lines means
absolute value, meaning that negative numbers become positive. The first step is to
calculate the error (difference between estimation and exact answer). This is accomplished by subtracting the estimated answers from the exact answer or
vice versa (it does not matter which way around as long as you ignore any - signs). Then, you divide the error which you found in the first step by the exact
value which will give you a decimal. The last step is to convert the decimal into a percentage by multiplying it by 100 and adding the % sign. This gives you
the percentage error. There are a few examples underneath.
Continue Estimating
I hope these few lessons on estimation have helped you. You should continue developing your estimation skills as they are very
important in life. Make sure to also check out some other topics on this website by visiting the library. Please share this page if you
like it or found it helpful!
Example 1
Estimation = 120 Exact Answer = 129
In this example, we have found the error which
was 9 which we then divided by the exact value
before converting it into a percentage.

Example 2
Estimation = 350 Exact Answer = 357.64
In this example, we have found the error which
was 7.64 which we then divided by the exact value
before converting it into a percentage.

Example 3
Estimation = 170 Exact Answer = 167.5
In this example, we have found the error which was 2.5 which we then divided by the exact value before converting
it into a percentage.

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Chapter 5.2: Learning Outcomes
Students will know what the percentage error shows!
Students will have the ability to calculate percentage error!
Students will be introduced to the concept of absolute value!

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