trailing cumulative sum formula
I have what is likely to be a very easy formula need. I have a temperature dataset and need to calculate a trailing cumulative sum over the past 120 days (known as "degree-heating weeks" since I will convert this sum to weeks by dividing by 7). I know how to get a trailing average, and I know how to get a cumulative sum, but is it possible to get a trailing, 120-day cumulative sum? In this case, w...