New Home Forums Math Olympiad - RMO and INMO Quarry on Mirror reflection

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  • #77196
    Sonakshi Das
    Participant

    <p>The time shown by a digital clock at 21: 15 has the curious property that it reads exactly the same after reflection in a vertical mirror. How many such times are there in the course of 24 hour clock.</p>

    #77208
    Saumik Karfa
    Participant

    From the image you can see  2' s reflection is 5 / 1's reflection is 1 / 8's reflection is 8 / 0's reflection is 0.

    so you have to make a 4 digit number with the digits 2,5,8,1,0 such that the reflections are in symmetric position.

    Now make different cases.

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