Running Total Difference between each Time Period

Hi nates05 ,

You can try my method:
At first, create a new column "rank".

rank =
RANKX ( 'Table', 'Table'[Period],, ASC, DENSE )

Then create your goal column.

Sold per period =
VAR a =
    CALCULATE (
        FIRSTNONBLANK ( 'Table'[Total Sold], 1 ),
        FILTER (
            'Table',
            'Table'[Serial Codes] = EARLIER ( 'Table'[Serial Codes] )
                && 'Table'[rank]
                    = EARLIER ( 'Table'[rank] ) - 1
        )
    )
RETURN
    'Table'[Total Sold] - a

Here is the result.

Best Regards,

Eads

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