题目内容
【题目】用简便方法计算。
①4×0.8×2.5×12.5
②0.65×14+87×65%-65%
③42÷[14-(50-39)]
④2.25×4.8+77.5×0.48
【答案】100,65,14,48
【解析】①4×0.8×2.5×12.5,
=(4×2.5)×(0.8×12.5),
=10×10,
=100;
②0.65×14+87×65%-65%,
=0.65×14+87×0.65-0.65×1,
=0.65×(14+87-1),
=0.65×100,
=65;
③42÷[14-(50-39)],
=42÷[14-11],
=42÷3,
=14;
④2.25×4.8+77.5×0.48,
=2.25×4.8+7.75×4.8,
=(2.25+7.75)×4.8,
=10×4.8,
=48。
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