Excel normally recalculates all cells in a workbook automatically when the value in any cell changes. But if you work with complex workbooks, you may need to turn off automatic recalculation (on the Calculation tab of the Options dialog box) to prevent lengthy recalculation from slowing down your work. You can then force recalculation manually when needed by using the following keyboard shortcuts.
[F9]
This command recalculates all the cells that have changed and the cells they affect. If the workbooks are highly complex, recalculation may take a long time.
[Shift] - [F9]
If your changes are limited to the active worksheet, use this shortcut to restrict recalculation to that worksheet.
[Ctrl] - [Alt] - [F9]
This command recalculates even cells that have not changed. You shouldn t need to use it often.
[Ctrl] - [Alt] - [Shift] - [F9]
This Vulcan Nerve Pinch four-key shortcut is the ultimate in recalculation: Excel rechecks all formulas in all the worksheets in the open workbooks, then recalculates all the cells, even those that have not changed.