> H2 = c(2700,2600, 3050, 2900, 3000, 2500, 2600, 3000, 2800, + 3200, 2800, 3400) > cumsum(H2) [1] 2700 5300 8350 11250 14250 16750 19350 22350 25150 28350 [11] 31150 34550 > diff(H2) [1] -100 450 -150 100 -500 100 400 -200 400 -400 600We see that there were 34,550 sold, December had the greatest increase (600), and June had the largest decrease (-500).