Excel 2010 :: How To Hide Unwanted Values Created By Formulas

I am trying to create an inventory list that automatically updates the supply quantity when items are taken away from inventory. I have created entry cells where the quantity of items taken out of inventory can be entered (example, cell F2 of the attachment), and the new overall inventory count is adjusted accordingly for each stock of items (example, cell B3). These automated adjustments are repeated for each subsequent row for every time items have been taken from inventory and recorded.

I managed to get it to do what I originally intended with exception of the fact that it still present values on rows where there were no activity - or quantity of items taken from out of inventory (row #6 and beyond of the attachment). Is there a way of "hiding" these values without removing the formula, or possibly set conditional formatting where no values are displayed if no changes in inventory has been entered?

Example.xlsx

Using Excel 2010