Macros to check if any cell value has changed before closing workbook

I need to write macro to check if any cell value has changed in the workbook and present a message if it has, when closing the workbook? any ideas how can it be done? Any help is appreciated.

From my understanding, if no changes had been made to a workbook, then the user would not receive a Save prompt when closing the workbook.

Alternately you could use the worksheet change event to add a YES to a specified cell, then use the workbook before close event to check to see if a YES is found in the cell.

You would have to use the Workbook Open event to clear the YES though.

Thanks a lot for your reply. This idea is enough for me to go ahead with the macro.