Retailers and major supermarkets combat inventory abnormalities in what is probably the most efficient way possible.
When an item is scanned at the cash register for purchase, that information is placed in the company's inventory database and, in most cases, a new unit is automatically ordered to replace the one that is sold.
This one-for-one system eliminates the need to determine how many of a product should be ordered. Plus, the software can help a company see which products sell best under which circumstances.
Of course, this system can't address all discrepancies. For example, if a customer returns an undamaged item, that item may be put back on the shelf, even though a new one has been ordered.