其它
Calculate the value of $$7 + 16 + 34 + 45 + 50 - 6 - 15 - 4 - 7$$. 
Overseas Competition->Knowledge Point->Counting Modules->Law of Addition and Multiplication->Law of Addition
$$7-7 + 16-6 + 34-4 + 45-15 +50$$  $$= 0+10+30+30+50$$  $$= 120$$ 