Excel is incredibly powerful when your data is complete, but what happens when you need to solve for unknown variables? Enter Goal Seek and the Solver add-in, two tools that let Excel do the heavy ...

The popular Solver for Excel add-on has been redeveloped for Excel 2008 by Frontline Systems and Microsoft.

For Excel, you need to install the Solver add-in (go to the Excel Options dialog, select Manage Add-Ins, and select the Solver Add-In). You might also enjoy OpenSolver.