Hello,   I have searched all over and can't seem to find an answer for this. For each row, I am attempting to sum the values of the next x rows (3 in the example below) for each item.   Example: Item 1, row count for aggregation = 3, next 3 rows countain 10 in each row which equals a sum of 30.  It only sums for the item that corresponds to the row that the sum calculation is on (similar to a group by).    The example below is far simpler than my real data which contains different values for sales for each row. I am assuming that this would be an iterating do until loop of some sort but I can't seem to think of a strategy.  Thanks for all of your insight!   Item Sales SumRolling 1 10 30 1 10 30 1 10 30 1 10 30 1 10 30 1 10 30 1 10 20 1 10 10 2 20 60 2 20 60 2 20 60 2 20 60 2 20 60 2 20 40 2 20 20 ... View more