南京朗诗玲珑屿二手房:脑算乘法第52讲

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脑算乘法第52讲

(2009-04-02 08:29:57)转载 标签:

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脑算乘法第52讲

三位数平方,自身加减后两位:自身加后两位数,乘自身减后两位数,再加上后两位数的平方。

     3462=(346+46)×(346-46)+46         

         =392×300+2116                                      

         =117600+2116                                           

         =119716

      6372=674×600+372

          =404400+1369

          =405769

     5272=554×500+272                      

         =277000+729                          

         =277729                              

     8542=908×800+542

         =726400+2916

         =729316

     4562=512×400+562                      

         =204800+3136                          

         =207936                        分享

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