Question

    There is a numeric lock which has a 3-digit PIN. The

    PIN contains digits 1 to 7. There is no repetition of digits. The digits in the PIN from left to right are in decreasing order. Any two digits in the PIN differ by at least 2. How many maximum attempts does one need to find out the PIN with certainty?
    A 6 Correct Answer Incorrect Answer
    B 8 Correct Answer Incorrect Answer
    C 10 Correct Answer Incorrect Answer
    D 12 Correct Answer Incorrect Answer

    Solution

    The correct answer is D

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