"Ken" wrote...
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I am looking for a formula or function in excel that will result in 166.67.
Note that 166.67 - (166.67 * 40%) will result in my original number of 100.
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Just a little algebra is all that's needed.

166.67 - (166.67 * 40%) = 166.67 * (1 - 0.40) = 100

so

100 / (1 - 0.40) = 166.67

So if you enter 100 as P and 40% as d, the formula to get 166.67 is P/(1-d).