9+99+999+9999简便算法?

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9+99+999+9999简便算法?9+99+999+9999简便算法?9+99+999+9999简便算法?9+99+999+9999=(10-1)+(100-1)+(1000-1)+(10000-1

9+99+999+9999简便算法?
9+99+999+9999
简便算法?

9+99+999+9999简便算法?
9+99+999+9999
=(10-1)+(100-1)+(1000-1)+(10000-1)
=11110-4
=11106

5

9+99+999+9999
=(10-1)+(100-1)+(1000-1)+(10000-1)
=10000+1000+100+10-4
=11106

=(10-1)+(100-1)+(1000-1)+(1000-1)
=(10+100+1000+10000)-4
=11110-4
=11106

9+99+999+9999
=(10-1)+(100-1)+(1000-1)+(10000-1)
=10000+1000+100+10-4
=11106

9+99+999+9999
=(10-1)+(100-1)+(1000-1)+(1000-1)
=(10+100+1000+10000)-4
=11110-4
=11106

9+99+999+9999
=(10+100+1000+10000)-4
=11110-4
=11106