徐矿集团天山矿业用电:脑算实例连载26

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脑算实例连载26

5、  乘数是75:被乘数折半、再折半,乘3或先乘3后折半、折半;

48×75=24             98×75=49         59×75=295          37×75=185

=12×3                =245×3           =1475×3            =925×3

=3600                 =7350             =4425               =2775

           或=48×3              或=98×3          或=59×3            或=37×3

             =144                  =294             =177                 =111

             =72                   =147             =885                 =555

             =3600                 =7350            =4425                =2775