Click any cell within the list range.
Click the Data tab.
Click the What-If Analysis button, and then click Goal Seek.
Click the Set Cell box, and then type the cell address.
Click the To Value box, and then type the result value.
Click the By Changing Cell box, and then type the cell address you want Excel to change.
Click OK.
The Goal Seek Status dialog box, opens displaying the goal seek results.