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A three-digit code for certain locks uses the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 according to the following constraints. The first digit cannot be 0 or 1, the second digit must be 0 or 1, and the second and third digits cannot both be 0 in the same code. How many different codes are possible?
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· 相关考点
6.3.1 基本计数原理与加法原理
6.3.1 基本计数原理与加法原理
以上解析由 考满分老师提供。
