9+99+999+9999+99999+999999+9999999+99999999+999999999等于多少?

9+99+999+9999+99999+999999+9999999+99999999+999999999等于多少?
9+99+999+9999+99999+999999+9999999+99999999+999999999等于多少?

9+99+999+9999+99999+999999+9999999+99999999+999999999等于多少?
9+99+999+9999+99999+999999+9999999+99999999+999999999
＝10-1+100-1+1000-1+10000-1+……+1000000000-1
＝1111111101

很简单，等于1111111101

9+99+999+9999+99999+999999+9999999+99999999+999999999
=10-1+100-1+1000-1+.......+1000000000-1
=1111111111-9
=1111111101

9+99+999+9999+99999+999999+9999999+99999999+999999999
＝（9+1）+（99+1）+（999+1）+（9999+1）+（99999+1）+（999999+1）+（9999999+1）+（99999999+1）+（999999999+1）-9
＝1111111110-9
＝1111111101
这题可以用凑数法计算，...

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9+99+999+9999+99999+999999+9999999+99999999+999999999
＝（9+1）+（99+1）+（999+1）+（9999+1）+（99999+1）+（999999+1）+（9999999+1）+（99999999+1）+（999999999+1）-9
＝1111111110-9
＝1111111101
这题可以用凑数法计算，也可以用拆分数字法计算。

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