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【计算:9+99+999+…+99999999+999999999=______.】
计算:9+99+999+…+99999999+999999999=______.
1回答
2020-02-27 11:26
【计算:9+99+999+…+99999999+999999999=______.】
计算:9+99+999+…+99999999+999999999=______.
9+99+999+…+99999999+999999999
=(10-1)+(100-1)+(1000-1)+…+(100000000-1)+(1000000000-1)
=10+100+1000+…+100000000+1000000000-9
=1111111110-9
=1111111101;
故填:1111111101.