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用简便方法做下面两题:71.7×4.06-59.4×2.83=?36.8×8.4+14×0.17+38.5×1.6=?

来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/11/08 01:32:28
用简便方法做下面两题:71.7×4.06-59.4×2.83=?36.8×8.4+14×0.17+38.5×1.6=?
71.7×4.06-59.4×2.83=7.17×40.6-59.4×2.83
=(10-2.83)×40.6-59.4×2.83 =406-2.83×40.6-59.4×2.83
=406-(40.6+59.4)×2.83 =406-283=123
36.8×8.4+14×0.17+38.5×1.6=36.8×(10-1.6)+14×0.17+38.5×1.6
=368+1.6×(38.5-36.8)+14×0.17=368+1.6×1.7+14×0.17
=368+(16+14)×0.17=368+5.1=373.1