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  

2019-05-23 08:14
  173
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                   

                                                   
                         10+10+10+10+10                                       
                       10×1+10×2+10×3+10×4+10×5                                                                                                                 
                             101 +102 +103 +104+105                                                                                  
                                                                                                                                          



  
     
     