Excell formula

I want to aadd a formula in an Excell 2003 spreadsheet.

The formula has to clear the content of a group of cells if another cell gives a certain value.
houw do i do this

kind regards

I think you can only do this by writing a macro using Visual Basic for Applications.

Thanks for the answer, that is what i toughth to.
but i don’t no how to write in visual basic can you help me?