9+99+999+9999+99999的简便运算

急！！！！！！

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原档凳式=（9+1）+（悉虚99+1）+（999+1）+（9999+1）+（行陆旅99999+1）-5
=10+100+1000+10000+100000-5
=111110-5
=111105

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=10-1+100-1+1000-1+10000-1+100000-1

=111110-5

=111105

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