Not going to even guess why you want to do this. But, this is solved rather easily with a few table calculations. I've created two new fields. One of which is just renaming your running total. This field is a running total going across the table. Starting left to right.
I then created a second field which using that running total that runs across but uses a lookup function to literally look up the row above it and return a value for a specific field. Once that field is created we had to edit the table calculation as it is nested (multiple table calculations). When you are in the edit table calculation menu you will have a dropdown menu. Drop down to the 'running total across' its setting is running across. Then make sure the division looking up is set to table down.
Because we are looking up in both the multiplication and division bits and in the same direction I was able to put these in the same level of table calculation. I've attached your workbook with the corrected fields.
Unsure how you wanted to handle areas that did not yet have values so I left null handling up to you.
Help.twbx 65.0 KB