Consumption at unit

Dear Gurus

I have query, when ever warehouse issuing the material or chemical to unit for consumption, as per sap material hasbeen consumed and accounted, BUT here my query is that, If any material has pack of 5KG, and i got it from ware house but my consumption is only 2KGS, then How can track rest of the stock, Is there any suggestions.

Ex:- 5KGs issued from ware shouse

2KG is my consumption

3KG is still available with me, what is the way to manage this quantity in sap.

Best Regards

srinivas