what if

Excel 2003 does not use the overcharged term: “sensitivity.” Having avoided this trap, Excel falls into another. It has so many features that fall under Sensitivity Analysis that one remains ignorant of how much Excel can do in this area and where these facilities are.
For example, there is an entry on the Data menu called [...]

This post shows an example of NPV and IRR formulations using sensitivity analysis in Excel. Graphic representation show the cross over of NPV and hence give IRR directly.