0.9+1.9+29.9+399.9+4999.9简算

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0.9+1.9+29.9+399.9+4999.9简算

0.9+1.9+29.9+399.9+4999.9简算
0.9+1.9+29.9+399.9+4999.9简算

0.9+1.9+29.9+399.9+4999.9简算
0.9+1.9+29.9+399.9+4999.9=(0.9+0.1-0.1)+(1.9+0.1-0.1)+(29.9+0.1-0.1)+(399.9+0.1-0.1)+(4999.9+0.1-0.1)=(1-0.1)+(2-0.1)+(30-0.1)+(400-0.1)+(5000-0.1)=1+2+30+400+5000-0.1×5=5433-0.5
=5432.5

0.9+1.9+29.9+399.9+4999.9=0.9+1.9+29.9+399.9+4999.9+0.5-0.5=1+2+30+400+5000-0.5=5432.5

=(1+2+30+400+5000)-0.1x5

原式可化为1+2+30+400+5000-0.1×5

(0.9+0.1+1.9+0.1+29.9+0.1+399.9+0.1+4999.9+0.1)-0.1×5
=5433-0.5
=5432.5