and as you can see there are multiple, same numbers in column A. Based upon a unique value in A, I need to determine a sum of values for Quantity then a sum of values for Line Item Value, etc.
Anyone want to take stab and not laugh because I am making this more complicated than it is?
I previously tried your solution using LinQ as well. Already have the distinct items. The problem I am particularly running into is that when adding the data rows to a cloned DT it is generating a duplicate line for each line in the loop (There are several thousand distinct items each month). I eventually just threw in a remove duplicate lines from the cloned Dt and it is fine. Takes a little longer than I wanted but it is what it is.
Grouping seems ideal if we are only working with one column that needs to be aggregated. I have several columns that need aggregated hence why I was trying for a different solution with LinQ