Create a new dynamic column with the sum of last N column

[Cagahan]

Hello everyone, i have a workflow which refreshes everyday with the previous day's sales. 

I created a table where i can see the sales of last two weeks of the sites day by day. I would like to create a column to the end, where i sum up the sales of the last 3 days (or last n days) of sites. The data will be updated daily and the column names will be updated accordingly so it needs to be dynamic.

An example table: 

	19.09.2023	20.09.2023	21.09.2023	22.09.2023	23.09.2023	Total of Last 3 Days
Site A	10	9	4	10	9	23
Site B	11	12	11	4	12	27
Site C	8	3	8	1	3	12
Site D	3	1	3	6	1	10

Hope that was clear enough! 

Thank you in advance

[binuacs · Accepted solution]

@Cagahan One way of doing this

[Cagahan]

Thank you binuacs, i understood the logic.

However, i am having trouble to output "dates", which i believe it is a format issue. Dynamic Select tool only brings the Site, but not the dates.

Date column comes from the formula tool with following formula:

DateTimeFormat(DateTimeParse([KAYIT TARİHİ],"%Y-%m-%d %H:%M"), "%d-%m-%Y")

Really appreciated in advance!

[Cagahan]

It was date format issue and i figured it out. Your solution works perfectly! Thank you!