Goal Seek is Excel’s

Goal Seek is Excel’s built-in What-If Analysis tool that shows how one value in a formula impacts another. More precisely, it determines what value you should enter in an input cell to get the desired result in a formula cell.
The best thing about Excel Goal Seek is that it performs all calculations behind the scenes, and you are only asked to specify these three parameters:
• Formula cell
• Target/desired value
• The cell to change in order to achieve the target
The Goal Seek tool is especially useful for doing sensitivity analysis in financial modeling and is widely used by management majors and business owner. But there are many other uses that may prove helpful to you.