In book.xlsx, column B contains 30 daily values (rows 2-31). Fill column C with the trailing 7-day moving average starting at row 8 (i.e. C8 = average of B2:B8, C9 = average of B3:B9, ..., C31 = average of B25:B31). Leave C2:C7 empty. Use number format "0.00" for the moving-average cells. Save in place.
