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999……9(1999个9)*9999……9(1999个9)*1999……9(1999个9),乘积等于多少?

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999……9(1999个9)*9999……9(1999个9)*1999……9(1999个9),乘积等于多少?
999……9(1999个9)*9999……9(1999个9)*1999……9(1999个9),
=[100...0(1999个0)-1][100...0(1999个0)-1][100...0(1999个0)-1]
=[100...0(1999个0)-1]^3
=100...0(1999个0)^3-3*(100...0(1999个0)^2+3*100...0(1999个0)-1
=100...0(5997个0)-3000.0(3998个0)+300.0(1999个0)-1
(根据(a-b)^3=a^3-3a^2b+3ab^2-b^3)