Each week, I will delete one of the columns (it's a set of forecasts held together by a week number at the head of the column; e.g., this week is week 46).
I want to add the next x number of cells together. This (x) may change; I'll use 20 as an example. This will give me the sum of the next 20 cells in that row. I then want to do it for the next row below that, etc.