Usually we multiply the result with 100 in order to get the percentage difference in numbers. If you were to find percent change manually you would take an old original value and a new value find the difference between them and divide it by the original value. In the example shown E6 contains this formula.
The difference formula gives us the difference between the two numbers as a fraction of the base number 120.
You can clearly see how the result from the example is 100 because the number 150 is between 100 and 999. The percentage between the two values is simply calculated by taking the difference between two numbers and dividing it with the original number. To find the percentage difference between any two numbers first subtract the smallest number from the bigger digit and then divide the outcome of subtraction with the smallest number among them. The change is usually a difference between the two values in context.