Page 677 - Excel 2013 All-in-One For Dummies

the value by clicking OK, remember that you can still switch between the “before” and “after” input values and results by clicking the Undo button on the Quick Access toolbar or by pressing Ctrl+Z.
To flip back and forth between the “after” and “before” values when you’ve closed the Goal Seek Status dialog box, press Ctrl+Z to display the original values before goal seeking and then Ctrl+Y to display the values engendered by the goal-seeking solution.
Figure 1-11:
A spreadsheet showing
a goal- seeking solution and the Goal Seek Status dialog box.
Using the Solver
Although the Data Table and Goal Seek commands work just fine for simple problems that require determining the direct relationship between the inputs and results in a formula, you need to use the Solver add-in when deal- ing with more complex problems. For example, use the Solver to find the best solution when you need to change multiple input values in your model and you need to impose constraints on these values and/or the output value.
The Solver add-in works by applying iterative methods to find the “best” solution given the inputs, desired solution, and the constraints that you impose. With each iteration, the program applies a trial-and-error method (based on the use of linear or nonlinear equations and inequalities) that attempts to get closer to the optimum solution.
When using the Solver add-in, keep in mind that many problems, especially the more complicated ones, have many solutions. Although the Solver returns the optimum solution, given the starting values, the variables that can change, and the constraints that you define, this solution is often not the only one possible and, in fact, may not be the best solution for you. To be sure that you are finding the best solution, you may want to run the Solver more than once, adjusting the initial values each time you solve the problem.
Using the Solver 659
Book VII Chapter 1
Performing What-If Scenarios