Hi Travis,
Let's compute it like it use too be!

Ending Inventory
+Cash in drop box
+Markers (copy of marker issued at table)
+Credit slips (copy of slip sent to cage with chips)
+Foreign chips or tokens
-Fills (copy of slip sent to cage)
-Opening inventory(based upon same amount established at opening of table for that pit)

=drop also can be known as table win and/or loss. It can be compared to itself or all other tables of similar limit, etc. etc.

This is how I teach it. Best, Jim