9.9+99.9+999.9+9999.9+1=?
简便计算
9.9+99.9+999.9+9999.9+1 =9.9+99.9+999.9+9999.9+0.1+0.1+0.1+0.1+0.6 =10+100+1000+10000+0.6 =11110.6
9.9+99.9+999.9+9999.9+1 =9.0+99.0+999.0+9999.0+1 =11113+0.9x4 =11116.6
9+99+999+999+1+1*4-0.1*4+1=10+100+1000+10000-0.4+1=11110-+1-0.4=11109.6+1=11110.6
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