Need a DAX measure to replace an Excel function.

Hi there,

I wish everyone was as clear in describing their needs! :) 

I think the below will help you.

I simply created the running total for both columns, devided it and *1000.

Calc = 

DIVIDE(
CALCULATE(
	SUM('Table'[Number of Complaints]);
	FILTER(
		ALLSELECTED('Table'[Month]);
		ISONORAFTER('Table'[Month]; MAX('Table'[Month]); DESC)
	)
); CALCULATE(
	SUM('Table'[Number of Key Transactions]);
	FILTER(
		ALLSELECTED('Table'[Month]);
		ISONORAFTER('Table'[Month]; MAX('Table'[Month]); DESC)
	)
)
)*1000

Hope this helps.