题目内容
简便方法计算
1.7+5
+3.98
17.625-(4.4+7
)
3.35×6.4×2+6.7×3.6.
解:(1)1.7+5
+3.98,
=1.7+5.02+3.98,
=1.7+(5.02+3.98),
=1.7+9,
=10.7;
(2)17.625-(4.4+7
),
=17.625-(4.4+7.625),
=17.625-4.4-7.625,
=(17.625-7.625)-4.4,
=10-4.4,
=5.6;
(3)3.35×6.4×2+6.7×3.6,
=3.35×2×6.4+6.7×3.6,
=6.7×6.4+6.7×3.6,
=(6.4+3.6)×6.7,
=10×6.7,
=67.
分析:(1)把分数化为小数,运用加法结合律计算;
(2)把分数化为小数,与用减法的性质以及加法交换律和结合律简算;
(3)先运用乘法交换律计算3.35×6.4×2=3.35×2×6.4=6.7×6.4,原式变为6.7×6.4+6.7×3.6,再运用乘法分配律的逆运算简算.
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.
![](http://thumb.1010pic.com/pic5/latex/7893.png)
=1.7+5.02+3.98,
=1.7+(5.02+3.98),
=1.7+9,
=10.7;
(2)17.625-(4.4+7
![](http://thumb.1010pic.com/pic5/latex/5192.png)
=17.625-(4.4+7.625),
=17.625-4.4-7.625,
=(17.625-7.625)-4.4,
=10-4.4,
=5.6;
(3)3.35×6.4×2+6.7×3.6,
=3.35×2×6.4+6.7×3.6,
=6.7×6.4+6.7×3.6,
=(6.4+3.6)×6.7,
=10×6.7,
=67.
分析:(1)把分数化为小数,运用加法结合律计算;
(2)把分数化为小数,与用减法的性质以及加法交换律和结合律简算;
(3)先运用乘法交换律计算3.35×6.4×2=3.35×2×6.4=6.7×6.4,原式变为6.7×6.4+6.7×3.6,再运用乘法分配律的逆运算简算.
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.
![](http://thumb2018.1010pic.com/images/loading.gif)
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