Oops. You are correct, I have a mistake in the spreadsheet calculations.

I forgot to mention in my original post that the product is liquid and stored in a tank. As new receipts come in, they are mixed with the current inventory, changing the overall ingredient percents, so that the next shipment must take into consideration the new percents.

I have been looking at Jeff Moden's article about Quirky Updates and wonder if somehow I can use that logic. The biggest issue I see is that I have multiple "running total" variables to keep track of (several ingredients for the same product) so I'm not sure if I can make it work. Has anyone used any variation of the Quirky Update that might work for this?