Hi,

If you want to calculate accumulated sum, you can use a DAX formula to loop over your data , for example, you have a 'DataTable':

DateKey Value accumulate

001 3 3

002 2 5

003 1 6

accumulate can be calculated as

= Calculate(sum('DataTable'[Value]), Filter('DataTable', 'DataTable'[DateKey] <=earlier('DataTable'[DateKey]) ))

This makes more sense when you are trying to calculate regarding a numerical or a datetime field

In your example, the order of strings "Monday", "Tuesday"... is not defined so it does not make much sense to calculate incremental sums