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用简便方法计算下面各题(1)2.45×1.9+0.245×91-24.5;(2)(1.72+1.75+1.78)÷(1.73+1.74+1.75+1.76+1.77).

题目详情
用简便方法计算下面各题
(1)2.45×1.9+0.245×91-24.5;
(2)(1.72+1.75+1.78)÷(1.73+1.74+1.75+1.76+1.77).
▼优质解答
答案和解析
(1)2.45×1.9+0.245×91-24.5=2.45×1.9+2.45×9.1-2.25×10=2.45×(1.9+9.1-10)=2.45×1=2.45;(2)(1.72+1.75+1.78)÷(1.73+1.74+1.75+1.76+1.77)=(1.75×3)÷(1.75×5)=1.75×31.75×5=0.6...