You need a couple of extra parenthesis and also there is no need to use TRUE

=IF(ISERROR(((B15+B18)-(B16+B18))/(B15+B18)),"",((B15+B18)-(B16+B18))/(B15+B18))



--
Regards,

Peo Sjoblom


"Rich" .(donotspam) wrote in message
...
The formula is
=IF(ISERROR((B15+B18)-(B16+B18)/(B15+B18)=TRUE),"",(B15+B18)-(B16+B18)/(B15+B18))
Values are B15 = 10
B16 = 1
B18 = 1
Number format is percent with no decimal.
--
Rich


"Rich" wrote:

I am using a formula to calculate service level percentage. The answer
displays as 1082% and should be 82%

Thanks for the help,
--
Rich