Running Count Inventory Management Calculations

Hello! i have been using monday for about a month now and i have built out a pretty complex system of inventory management with over 700 boxes and 20,000 items in my warehouse that i work at. We have each box with a printed QR code on it with a link to each line item on monday, each item on monday has that box number and the count of how many t shirts are in each box. In order to change the T shirt count, i have to do that math in my head and then re write a the whole new shirt count on mobile. I would love if there were some way that I can have a live count of what i have, having a column do simple calculations, like 27-13. yes its possible in my head, but its just another place to make an error. even something as simple as a SUM( ) in a cell that i can edit on mobile would work but the formula column is not editable on mobile.