用你喜欢的方法计算 12.5×32×0.8-+2.5×[(3.2+1.8)÷0.25]6.4×0.09+0.01×6.4.
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解:①12.5×32×0.8,
=(12.5×8)×(4×0.8),
=100×3.2,
=320;
②-+,
=-+,
=;
③2.5×[(3.2+1.8)÷0.25],
=2.5×[5÷0.25],
=2.5×20,
=50;
④6.4×0.09+0.01×6.4
=6.4×(0.09+0.01),
=6.4×0.1,
=0.64.
解析分析:①12.5×32×0.8把32拆成8×4,根据乘法的结合律变成(12.5×8)×(4×0.8)计算简便;②-+,先通分在计算;③2.5×[(3.2+1.8)÷0.25]按四则运算的顺序计算;④6.4×0.09+0.01×6.4运用乘法的分配律变成6.4×(0.09+0.01)计算简便.
点评:完成本题要注意分析式中数据,运用合适的简便方法计算.