x = {88.8, -11.1, 22.3, -2.0, 5.0, -5.0, 6.0, -7.0, 8.0, -9.0}
sum(x,0) = 0.0
sum(x,1) = 88.8
sum(x,2) = 77.7
sum(x,3) = 100.0
sum(x,4) = 98.0
sum(x,5) = 103.0
sum(x,6) = 98.0
sum(x,7) = 104.0
sum(x,8) = 97.0
sum(x,9) = 105.0