I have a worksheet that lists amount of rainfall by area per hour. Each hourly measurement goes in a cell horizontally from column C to M, the first area is in row 7 and the last area is in row 47. The total is shown in column N.

Now that winter is coming up, I cannot use the same unit (mm) since snow here is measured in cm. Is there a way to automate the unit shown? I was wondering whether by typing in the letter 'R' or 'S' in the next column, a script would recognize that and add the unit automatically