Perhaps something like this in say, O4:
=IF(ISERROR(M4),H4*N4,H4*N4*M4)

Above assumes that if M4 returns #DIV/0!,
to proceed with just: H4*N4, otherwise do: H4*N4*M4
Check that the this logic is okay with your intents.
--
Max
Singapore
http://savefile.com/projects/236895
xdemechanik
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"David" wrote:
I have a formula problem and i would be greatful if anyone can help. I have 3
cells which i want to multiply together H4,N4,M4. However the cells already
have the following formula in it H4 =1/COS((G4*PI()/180)), M4
=1/COS((L5*PI()/180)) and N4 just has a number in it. There will not always
be a value in M4 and the cell displays #DIV/0! How do i get excel to
calculate H4*N4*M4 regardless of there being a value in M4 but to include M4
if there is a value in it?