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这些怎么巧算0.64×9.90.99×1.0011.02×4.75

题目详情
这些怎么巧算 0.64×9.9 0.99×1.001 1.02×4.75
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答案和解析
0.64×9.9
=0.64×(10-0.1)
=0.64×10-0.64×0.1
=6.4-0.064
=6.336
0.99×1.001
=0.99×(1+0.001)
=0.99×1+0.99×0.001
=0.99+0.00099
=0.99099
1.02×4.75
=(1+0.02)×4.75
=4.75+0.02×4.75
=4.75+0.095
=4.845