计算下面各题,能简算的要用简便方法计算.80-12×4÷3 60+180÷20-5 4.5-(2.68+0.86)15.37-2.8-2.2 19.92+10.35-9.92 42×4×25

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计算下面各题,能简算的要用简便方法计算.80-12×4÷3 60+180÷20-5 4.5-(2.68+0.86)15.37-2.8-2.2 19.92+10.35-9.92 42×4×25
计算下面各题,能简算的要用简便方法计算.
80-12×4÷3 60+180÷20-5 4.5-(2.68+0.86)
15.37-2.8-2.2 19.92+10.35-9.92 42×4×25

计算下面各题,能简算的要用简便方法计算.80-12×4÷3 60+180÷20-5 4.5-(2.68+0.86)15.37-2.8-2.2 19.92+10.35-9.92 42×4×25
80-12×4÷3 = 80 - 4×(12÷3)= 80 - 4×4 = 80 - 16 = 64
60+180÷20-5 = 60 + 9 - 5 = 64
4.5-(2.68+0.86)=4.5 -(2.7-0.02+0.8+0.06)=4.5 -(3.5+0.04)= 4.5 - 3.5 - 0.04 =0.96
15.37-2.8-2.2 = 15.37 - (2.8+2.2)=15.37 - 5 = 10.37
19.92+10.35-9.92 =10.35 + (19.92 - 9.92)=10.35 + 10 = 20.35
42×4×25 = 42×(4×25)= 42 ×100 = 4200