If your YES/NO is in B10, then your formula would be
=IF(B10="YES",B9*B8*0.5,"whatever you want if the answer isn't YES")
If you want the result to be blank if B10 is not YES, then
=IF(B10="YES",B9*B8*0.5,"")
--
David Biddulph

"shane" wrote in message
...
hi all,
i'm making a questionnaire/calculator and have added a YES/NO drop down
menu.
If the users selects "YES" i'd like excel to execute the following
equation
B9*B8*0.5

but haven't been able to work out how to do it. any help would be greatly
received.

shane