简便计算
①70.8-1.25-1.75??②5.81+8.3+4.19+11.7??③3.54×0.29-0.29×2.54??④0.25×17.3×0.4⑤7.2×9.9???????⑥48×0.69+3.1×4.8.
简便计算①70.8-1.25-1.75??②5.81+8.3+4.19+11.7??③3.54×0.29-0.29×2.54??④0.25×17.3×0.4⑤7.2×
答案:2 悬赏:30 手机版
解决时间 2022-01-01 08:50
- 提问者网友:浮克旳回音
- 2021-12-31 13:18
最佳答案
- 五星知识达人网友:詩光轨車
- 2021-12-31 13:23
解:(1)70.8-1.25-1.75,
=70.8-(1.25+1.75),
=70.8-3,
=67.8;
(2)5.81+8.3+4.19+11.7,
=(5.81+4.19)+(8.3+11.7),
=10+20,
=30;
(3)3.54×0.29-0.29×2.54,
=(3.54-2.54)×0.29,
=1×0.29,
=0.29;??
(4)0.25×17.3×0.4,
=0.25×0.4×17.3,
=0.1×17.3,
=1.73;
(5)7.2×9.9,
=7.2×(10-0.1),
=7.2×10-0.1×7.2,
=72-0.72,
=71.28;
(6)48×0.69+3.1×4.8,
=4.8×6.9+3.1×4.8,
=4.8×(6.9+3.1),
=4.8×10,
=48.解析分析:(1)运用减法的性质解答,(2)运用加法交换律和加法结合律解答,(3)(5)(6)运用乘法分配律解答,(4)运用乘法交换律解答.点评:本题主要考查学生正确选择四则运算简便算法解决问题的能力.
=70.8-(1.25+1.75),
=70.8-3,
=67.8;
(2)5.81+8.3+4.19+11.7,
=(5.81+4.19)+(8.3+11.7),
=10+20,
=30;
(3)3.54×0.29-0.29×2.54,
=(3.54-2.54)×0.29,
=1×0.29,
=0.29;??
(4)0.25×17.3×0.4,
=0.25×0.4×17.3,
=0.1×17.3,
=1.73;
(5)7.2×9.9,
=7.2×(10-0.1),
=7.2×10-0.1×7.2,
=72-0.72,
=71.28;
(6)48×0.69+3.1×4.8,
=4.8×6.9+3.1×4.8,
=4.8×(6.9+3.1),
=4.8×10,
=48.解析分析:(1)运用减法的性质解答,(2)运用加法交换律和加法结合律解答,(3)(5)(6)运用乘法分配律解答,(4)运用乘法交换律解答.点评:本题主要考查学生正确选择四则运算简便算法解决问题的能力.
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- 1楼网友:动情书生
- 2021-12-31 13:54
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