To calculate the original number based on current value and known percentage change, you can use a simple formula that divides the current value by the percent + 1. In the example shown, the formula in cell E5 is:


The results in column E are decimal values with the percentage number format applied.

Generic formula



In this example, the goal is to calculate the "original" number when the current value and percentage change are known. In other words, given that the current value is 1100 and the percentage change is known to be 10%, we want to return the starting value of 1000. 

The general formula for this calculation, where "x" is the original number, is:


Converting this to an Excel formula with cell references, the formula in E5 becomes:


As the formula is copied down, the formula returns the original price for each item in the table, based on the percentages shown in column C and the current values in column D.

Formatting percentages in Excel

In mathematics, a percentage is a number expressed as a fraction of 100. For example, 65% is read as "Sixty-five percent" and is equivalent to 65/100 or 0.65. Accordingly, the values in column C are decimal values, with the Percentage number format applied.

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Dave Bruns

Hi - I'm Dave Bruns, and I run Exceljet with my wife, Lisa. Our goal is to help you work faster in Excel. We create short videos, and clear examples of formulas, functions, pivot tables, conditional formatting, and charts.