# Running-Product

There may be occasion where you need to do a running product.

 Actual Running Total Running Product 3 3 3 6 9 18 8 17 144 2 19 288 1 20 288

Unfortunately there is no Cognos or database function to do this. Fortunately we have grade school math to come to the rescue! Thanks to the magic of natural logarithms, transcendentalism and running-totals we can make it happen.

The first step is to find the Natural Logarithm of the measure. Use the Cognos function ln: ln([Measures].[Count]). Wrap that in a running total running-total(ln([Measures].[Count])). Now we’ll use the transcendental number 2.71828… (or e) for short. e to the power of the running-total will return the running-product. exp(running-total(ln([Measures].[Count])))

```<report xmlns="http://developer.cognos.com/schemas/report/6.0/" expressionLocale="en-nz">
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