A three-digit code for certain logs uses the digits 0,1,2,3,4,5,6,7,8,9 according to the following constraints. the first digit cannot be 0 and 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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发表于 2008-9-10 22:46:00
