Since the top inventory value we can get is 999, we don’t have a way to have an accurate units sold value when the inventory is equal or greater than 999. This is why, when dealing when 999 inventory values in a listing (either in the inventory column or anything related to units sold), we display the “+” icon next to the value. Even though we guess there are more than 999 items on the inventory, for all calculations we use just the 999 items that we know about.