问题标题:
简便计算;1.9+1.99+1.999+1.9999+1.9999928*1111+9999*8
问题描述:

简便计算;1.9+1.99+1.999+1.9999+1.9999928*1111+9999*8

孙永军回答:
  1.9+1.99+1.999+1.9999+1.99999   =2-0.1+2-0.01+2-0.001+2-0.0001+2-0.00001   =10-0.11111   =9.88889   28*1111+9999*8   =28*1111+1111*9*8   =1111*(28+72)   =1111*100   =111100
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