How to Calculate a Trimmed Mean in Excel. A trimmed mean is much like a standard mean, which you can derive in Excel using the AVERAGE function. However, instead of using all of the data points to ...

Learn how to calculate the net present value (NPV) of your investment projects using Excel's XNPV function.

Add together all the cash flows you have put in the spreadsheet to calculate a total. Divide the total by the number of historical entries to calculate the mean average cash flow.