Inventory Adjustment

Front Accounting has 100 units in inventory but an actual inventory count of 200

I want to do an inventory adjustment but my concern is:

I will somehow effect the COGS per item on my I/S (I have the correct total cost in the GL for all the inventory we have purchased)

Should I put in the $10 per unit cost in the inventory adjustment entry or should I put $0.00?

Goal is that if I sell 10 units I want to see $100 in the COGS not something higher or lower.