I am trying to sum a series of data based on all totals from each week. In column G I have a list of quote totals, dollar amounts, In column I there is the "week of" date when the quote was given. Column I will have several with the same date and will only have date increments of 7 days. This report is updated weekly, the dates will always be 7 days apart. I have a formula that will sum on the first date and then the next to add 7 days then add 14 days then 21 days..... Can I tell Excel to automatically keep adding 7 days to the new formula?