Remember that percentage changes are always based on the original value.
As an example. Consider an article costing 200 pounds. This cost-price is increased by 10% to make the selling-price 200 + 20 = 220 pounds.
Now, someone who knows that 10% was put ON the cost-price, and can see the selling-price is 220 pounds, wishes to know what the cost-price was.
They might think like this: 10% of 220 = 22. So the cost-price must have been 220 - 22 = 198 pounds. Which we know is wrong!
This is a very common problem with goods which carry a tax.
Putting the percentage in the Percentage change and the selling-price in as the Value after increase will reveal the cost-price as the Original value
Fractions & Percentages
A common fraction is written as a number over another number with a line drawn between them. The top number is called the numerator and the bottom is the denominator. In this calculator it is possible to change a common fraction into its equivalent as a percentage.
Just put the numerator (=top number) in as Amount of change and the denominator (=bottom number) as Original value and press Calculate It and the value in Percentage change will be the equivalent of that common fraction.
In this calculator it is not possible to enter zero or negative numbers.
However it is possible, in some circumstances, that negative numbers may appear as one of the solution values. Whether these solutions are valid will depend upon the context in which the problem arises.