运用简便方法计算72×125?????????????99×38+38??????3200÷4÷25??????9.14-1.43-4.57??????1.88+2.

发布时间:2020-08-04 14:48:03

运用简便方法计算
72×125?????????????99×38+38??????3200÷4÷25??????9.14-1.43-4.57??????1.88+2.3+3.7??????98×47.

网友回答

解:(1)72×125,
=9×8×125,
=9×(8×125),
=9×1000,
=9000;

(2)99×38+38,
=(99+1)×38,
=100×38,
=3800;

(3)3200÷4÷25,
=3200÷(4×25),
=3200÷100,
=32;

(4)9.14-1.43-4.57,
=9.14-(1.43+4.57),
=9.14-6,
=3.14;

(5)1.88+2.3+3.7,
=1.88+(2.3+3.7),
=1.88+6,
=7.88;

(6)98×47,
=(100-2)×47,
=100×47-2×47,
=4700-94,
=4606.
解析分析:(1)把72看作9×8,运用乘法结合律简算;(2)把38看作38×1,运用乘法分配律简算;(3)运用除法的性质简算;(4)运用减法的性质简算;(5)运用加法结合律简算;(6)把98看作100-2,运用乘法分配律简算.

点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.
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