How to create a simplest inventory system using only pen and paper

I read recently in the book "Inventory accounting: a comprehensive guide" by Steven M.Bragg that :"Inventory is a difficult asset to control-it arrives and departs company premises daily, is scattered throughout the warehouse and production areas (and possibly offsite storage locations),may contain obsolete or scrap items ,can involve thousands of part numbers,can include items owned by suppliers or customers, and may be valued using a variety of techniques for both direct and overhead costs."
It's really true.But what should you do if you don't like computers but want to solve problems with you inventory? There's an old and true pen and paper solution.Take a few sheets of paper and draw the table as shown in Figure.

You have to create inventory cards for all items in your warehouse. Put them in a box and begin tracking of your inventory. You should do phisical count of your warehouse and enter current on hand quantity in the column IN for each good. You will enter any shipped quantity in the column OUT and received quantity in the column IN. Then,you should calculate BALANCE in mind or using any hand calculator. You will have a very simple but the real working inventory system. Of course, if you have a computer you can use a more convenient solutions for inventory accounting.