下列递等式如何巧算
24.44×2.5、7.7×10.01、29×0.29-2.9+29×0.81、38.2×0.98、4.31×0.99==========...
24.44×2.5、7.7×10.01、29×0.29-2.9+29×0.81、38.2×0.98、4.31×0.99
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2013-08-26 · 知道合伙人教育行家
wangcai3882
知道合伙人教育行家
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解:
24.44×2.5
=(20+4+0.4+0.04)×2.5
=20×2.5+4×2.5+0.4×2.5+0.04×2.5
=50+10+1+0.1
=61.1
7.7×10.01
=7.7×(10+0.01 )
=77+0.077
=77.077
29×0.29-2.9+29×0.81
=29×0.29-29×0.1+29×0.81
=29×(0.29-0.1+0.81)
=29×1
=29
38.2×0.98
=38.2×(1-0.02)
=38.2×1-38.2×0.02
=38.2-0.764
=37.436
4.31×0.99
=4.31×1-4.31×0.01
=4.31-0.0431
=4.2669
如果只写两个等号的话,你删除中间过程的等号,保留2个等号就行
24.44×2.5
=(20+4+0.4+0.04)×2.5
=20×2.5+4×2.5+0.4×2.5+0.04×2.5
=50+10+1+0.1
=61.1
7.7×10.01
=7.7×(10+0.01 )
=77+0.077
=77.077
29×0.29-2.9+29×0.81
=29×0.29-29×0.1+29×0.81
=29×(0.29-0.1+0.81)
=29×1
=29
38.2×0.98
=38.2×(1-0.02)
=38.2×1-38.2×0.02
=38.2-0.764
=37.436
4.31×0.99
=4.31×1-4.31×0.01
=4.31-0.0431
=4.2669
如果只写两个等号的话,你删除中间过程的等号,保留2个等号就行
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