= price / (1 - discount)

If you have a discounted price and know the discount percentage, you can calculate the original price with a simple formula that divides the discounted price by the result of 1 minus the discount percentage.

In the example, the active cell contains this formula:

=C6/(1-D6)

In this case, Excel first calculates the result of 1 - the value in D6 (.35) to get 0.65. Next the value in C6 (70), which represents the discounted or "sale" price, is divided by 0.65 to get a final result of 107.69:

=70/(1-0.35)

=70/0.65

=107.69