999…9(1988个9)*999…9(1988个9)+1999…9(1988个9)=?

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999…9(1988个9)*999…9(1988个9)+1999…9(1988个9)=?

=[1000...000(1988个0)-1]*[1000...000(1988个0)-1]+[2000...000(1988个0)-1]=1000...000(3976个0)-2*[1000...000(1988个0)-1]+1+2*[1000...000(1988个0)]-1=1000...000(3976个0)