You don't say what you start with but this might work
=100-sumif($b$2:$b$200,b2,$d$2:$d$200)

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Don Guillett
SalesAid Software

"Roelamp" wrote in message
...
I have set up a worksheet I have my 150 items in a list in say colum A I
would like to keep a running inventory for example:
date item cost sold avaliable
1/1/5 Dog 149.00 1 6
1/2/5 Cat 100.00 1 3
1/3/5 Dog 149.00 1 5

thanks for your help
Rosie