Let me try, the #'s should be 2+3+7+28=40 and it is suposed to work like 3-2 =1 2 = 2 3 = 3 7 - 3 = 4 2+3 = 5 7 + 2 - 3 = 6 7 = 7 7+ 3 -2 = 8 7 + 2 = 9 7 + 3 = 10 thereafter adding seperately the weight generated from above method 10 +1 =11 and so on. Since the conditions are not set, I believe this one also serves the purpose of weighing up to 40 Kgs.