This is a short guide on how to calculate the reverse percentage of a given number. i.e. You have the percentage number and the percentage, but you need to calculate the original number that it came from.

Take a look at the following PHP example, as the code will probably explain it better than words:

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//Our value, which we know is 77% //of the original number. $percentageValue = 72985; //The percentage value, which //we already know is 77. This is sometimes //called the final number. $percentage = 77; //Now, let's calculate the //original number. i.e. If 72985 is 77%, then //which number is it 77% of? $originalNum = ($percentageValue / $percentage) * 100; //In this case, 72985 is 77% of 94785.71 echo "$percentageValue is $percentage of $originalNum"; |

In the code snippet above, we know that 72,985 is 77% of * X*. However, we do not know what

*is.*

**X***in this case is the*

**X****original number**that 72,985 came from.

In order to calculate the **original number**, we need to do a reverse percentage calculation and divide the percentage into the percentage value. The percentage value is often referred to as the **final number**.

Once we divide the percent into the **final number**, we simply multiply the result by 100. This gives us the original number.

Note that if you want the **original number** in a format that only has two decimal places, you can simply use PHP’s **number_format** function like so:

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//Round it to two decimal places. $originalNum = number_format($originalNum, 2); echo $originalNum; |

This leaves us with 94,785.71. This makes sense, as 72,985 is 77% of 94,785.71.

To sum up the terms above:

**Final number**: 72,985**Percent**: 77%**Original number**: 94,785.71

Hopefully, this guide helped to clear a few things up!

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