用自己喜欢的方法计算下面各题.1.28+0.86+38.720.45÷0.6÷0.532×0.25×1.250.78÷0.13×0.213.6×9+40.6÷21.

发布时间:2020-07-31 15:49:46

用自己喜欢的方法计算下面各题. 1.28+0.86+38.720.45÷0.6÷0.532×0.25×1.250.78÷0.13×0.213.6×9+40.6÷21.08×0.8÷0.27.

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解:(1)1.28+0.86+38.72,
=(1.28+38.72)+0.86,
=40+0.86,
=40.86;

(2)0.45÷0.6÷0.5,
=0.45÷(0.6×0.5),
=0.45÷0.3,
=1.5;

(3)32×0.25×1.25,
=8×4×0.25×1.25,
=(4×0.25)×(1.25×8),
=1×10,
=10;

(4)0.78÷0.13×0.2,
=6×0.2,
=1.2;

(5)13.6×9+40.6÷2,
=122.4+20.3,
=142.7;

(6)1.08×0.8÷0.27,
=0.864÷0.27,
=3.2.

解析分析:(1)运用加法交换律与结合律简算;(2)运用除法的性质简算;(3)把32看作8×4,运用乘法交换律与结合律简算;(4)(6)从左往右依次运算;(5)先算乘除,再算加法.

点评:此题考查了小数的四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律进行简便计算.
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