put the sum in the row next to the lower item in the pairThat does not seem to be what you show in your example. Rather you seem to be showing the sum of a row and the row prior to it. In other words row 7 is 12.39 because that's the sum of -71.24 plus 83.63 and row 9 is 7.52 because that's the sum of 83.63 and -76.11.