Mirrored clocks

The name of the pictureThe name of the pictureThe name of the pictureClash Royale CLAN TAG#URR8PPP











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Triangulating for the simplest puzzle that is still at least somewhat interesting to solve..



On the left side wall in this picture, we have two particular clocks:



1: an analog clock with identical hour and minute arms, and



2: a digital clock that shows initial zeroes when appropriate




During the course of a day, which of these clocks agrees more often with its horizontal mirror image?




enter image description here










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  • The right side is a vertical reflection of the left side no? I don't understand what you mean by horizontal mirror image in this case.
    – Dorrulf
    2 hours ago










  • In the image, hour and minute hands appear to be the same length. Are we to make this assumption for figuring out how many times they "match"?
    – DqwertyC
    2 hours ago










  • @DqwertyC he describes the analog clock as having identical hour and minute arms, so yes, I think that is the assumption you should make. IE: The minute hand on the left may be visually equal to the hour hand on the right, and that is acceptable.
    – Dorrulf
    2 hours ago










  • @Dorrulf That's what I get for diving into the question without reading it thoroughly :P
    – DqwertyC
    2 hours ago










  • @Dorrulf The picture is supposed to depict a horizontal reflection (over a vertical plane). If I'm still being unclear, please imagine that the right hand wall is a mirror; that is the intended meaning.
    – Bass
    2 hours ago














up vote
3
down vote

favorite
1












Triangulating for the simplest puzzle that is still at least somewhat interesting to solve..



On the left side wall in this picture, we have two particular clocks:



1: an analog clock with identical hour and minute arms, and



2: a digital clock that shows initial zeroes when appropriate




During the course of a day, which of these clocks agrees more often with its horizontal mirror image?




enter image description here










share|improve this question





















  • The right side is a vertical reflection of the left side no? I don't understand what you mean by horizontal mirror image in this case.
    – Dorrulf
    2 hours ago










  • In the image, hour and minute hands appear to be the same length. Are we to make this assumption for figuring out how many times they "match"?
    – DqwertyC
    2 hours ago










  • @DqwertyC he describes the analog clock as having identical hour and minute arms, so yes, I think that is the assumption you should make. IE: The minute hand on the left may be visually equal to the hour hand on the right, and that is acceptable.
    – Dorrulf
    2 hours ago










  • @Dorrulf That's what I get for diving into the question without reading it thoroughly :P
    – DqwertyC
    2 hours ago










  • @Dorrulf The picture is supposed to depict a horizontal reflection (over a vertical plane). If I'm still being unclear, please imagine that the right hand wall is a mirror; that is the intended meaning.
    – Bass
    2 hours ago












up vote
3
down vote

favorite
1









up vote
3
down vote

favorite
1






1





Triangulating for the simplest puzzle that is still at least somewhat interesting to solve..



On the left side wall in this picture, we have two particular clocks:



1: an analog clock with identical hour and minute arms, and



2: a digital clock that shows initial zeroes when appropriate




During the course of a day, which of these clocks agrees more often with its horizontal mirror image?




enter image description here










share|improve this question













Triangulating for the simplest puzzle that is still at least somewhat interesting to solve..



On the left side wall in this picture, we have two particular clocks:



1: an analog clock with identical hour and minute arms, and



2: a digital clock that shows initial zeroes when appropriate




During the course of a day, which of these clocks agrees more often with its horizontal mirror image?




enter image description here







visual geometry time






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked 2 hours ago









Bass

23.8k458153




23.8k458153











  • The right side is a vertical reflection of the left side no? I don't understand what you mean by horizontal mirror image in this case.
    – Dorrulf
    2 hours ago










  • In the image, hour and minute hands appear to be the same length. Are we to make this assumption for figuring out how many times they "match"?
    – DqwertyC
    2 hours ago










  • @DqwertyC he describes the analog clock as having identical hour and minute arms, so yes, I think that is the assumption you should make. IE: The minute hand on the left may be visually equal to the hour hand on the right, and that is acceptable.
    – Dorrulf
    2 hours ago










  • @Dorrulf That's what I get for diving into the question without reading it thoroughly :P
    – DqwertyC
    2 hours ago










  • @Dorrulf The picture is supposed to depict a horizontal reflection (over a vertical plane). If I'm still being unclear, please imagine that the right hand wall is a mirror; that is the intended meaning.
    – Bass
    2 hours ago
















  • The right side is a vertical reflection of the left side no? I don't understand what you mean by horizontal mirror image in this case.
    – Dorrulf
    2 hours ago










  • In the image, hour and minute hands appear to be the same length. Are we to make this assumption for figuring out how many times they "match"?
    – DqwertyC
    2 hours ago










  • @DqwertyC he describes the analog clock as having identical hour and minute arms, so yes, I think that is the assumption you should make. IE: The minute hand on the left may be visually equal to the hour hand on the right, and that is acceptable.
    – Dorrulf
    2 hours ago










  • @Dorrulf That's what I get for diving into the question without reading it thoroughly :P
    – DqwertyC
    2 hours ago










  • @Dorrulf The picture is supposed to depict a horizontal reflection (over a vertical plane). If I'm still being unclear, please imagine that the right hand wall is a mirror; that is the intended meaning.
    – Bass
    2 hours ago















The right side is a vertical reflection of the left side no? I don't understand what you mean by horizontal mirror image in this case.
– Dorrulf
2 hours ago




The right side is a vertical reflection of the left side no? I don't understand what you mean by horizontal mirror image in this case.
– Dorrulf
2 hours ago












In the image, hour and minute hands appear to be the same length. Are we to make this assumption for figuring out how many times they "match"?
– DqwertyC
2 hours ago




In the image, hour and minute hands appear to be the same length. Are we to make this assumption for figuring out how many times they "match"?
– DqwertyC
2 hours ago












@DqwertyC he describes the analog clock as having identical hour and minute arms, so yes, I think that is the assumption you should make. IE: The minute hand on the left may be visually equal to the hour hand on the right, and that is acceptable.
– Dorrulf
2 hours ago




@DqwertyC he describes the analog clock as having identical hour and minute arms, so yes, I think that is the assumption you should make. IE: The minute hand on the left may be visually equal to the hour hand on the right, and that is acceptable.
– Dorrulf
2 hours ago












@Dorrulf That's what I get for diving into the question without reading it thoroughly :P
– DqwertyC
2 hours ago




@Dorrulf That's what I get for diving into the question without reading it thoroughly :P
– DqwertyC
2 hours ago












@Dorrulf The picture is supposed to depict a horizontal reflection (over a vertical plane). If I'm still being unclear, please imagine that the right hand wall is a mirror; that is the intended meaning.
– Bass
2 hours ago




@Dorrulf The picture is supposed to depict a horizontal reflection (over a vertical plane). If I'm still being unclear, please imagine that the right hand wall is a mirror; that is the intended meaning.
– Bass
2 hours ago










4 Answers
4






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up vote
2
down vote













The times where the analog clock will match are




The same as the times that the analog clock has reflective symmetry across it's "y" axis. This will happen at least once an hour. The proof for this involves the Intermediate Value Theorem, but essentially boils down to the fact that, every hour, the hour hand continuously sweeps one part of the clock, while the minute hand continuously sweeps the entire clock. It follows that, in sweeping the entire clock, it must for an instant pass through the part of the clock that is currently opposite the hour hand.


It actually matches slightly more often than this, because they're already matching at noon/midnight, so it comes out to 13 matches every 12 hours, or 26 total.




The times where the digital clocks will match are




Again, where the clock has reflective symmetry across it's "y" axis (The colon). As @Dorrulf has already enumerated, this happens at 00:00, 02:50, 20:05, and 22:55. I'm not counting the times with ones in them, because they don't show up on the same half of the digit when reflected. This is a measly 4 total




So, it's clear that the reflections match more often for the




Analog Clock







share|improve this answer



























    up vote
    0
    down vote













    Last try...




    As a forward, I'm going more for the idea that the clocks read identical times rather than they just look similar.
    The only analog positions I see matching would be at 12:30 and 3:45, and their self-reflections (6:00 and 9:15) for a total of 8 occurrences in 24-hr a day. (Thanks @ExcitedRaichu)

    The digital clock has a few things of note beforehand:

    The leading 0's and set to military time.

    Again, if we function with the idea that as long as the times read the same (and the positions don't have to be exact - left oriented 1 versus right oriented 1), then we have these reflective cases: 0 to 0, 1 to 1, 2 to 5, 5 to 2. We can't use 8 because minutes only goes to 60. This gives us the following combinations (barring any were missed): 01:10, 11:11, 10:01, 15:21, 12:51, 05:20, 02:50. @DqwertC also found: 00:00, 02:50, 20:05, and 22:55.

    That puts us at a ration of 8:11, in favor of the digital clock.







    share|improve this answer






















    • I'm still unsure of my understanding of "reflective agreement" though xD
      – Dorrulf
      1 hour ago










    • doesn’t (rot13) fvkbpybpx work for analog as well?
      – Excited Raichu
      1 hour ago










    • Also, most digital clocks don’t have an 0 in front of the hour number if it’s one digit
      – Excited Raichu
      1 hour ago











    • @ExcitedRaichu It explicitly says they do in the problem.
      – DqwertyC
      1 hour ago










    • @DqwertC whoops. missed that.
      – Excited Raichu
      1 hour ago

















    up vote
    0
    down vote













    Assuming 'agrees with' is synonymous with 'looks the same'...



    Analog




    As suggested by DqwertyC, the analogue clock will agree 26 times in 24 hours if you include both mid-nights. If you argue that there is only one midnight in a 24 hour day then this can be reduced to 25 times. Assuming the latter these times are approximately: 00:55, 1:50, 2:46, 3:41, 4:37, 5:32, 6:28, 7:22, 8:18, 9:14, 10:09, 11:04, and 12:00 plus the equivalent times in the afternoon.




    Digital




    As suggested by Dorrulf and DqwertyC there are a minimum of 4 times when the digital clocks agree (if only (2|5), and (0|0) digits are considered to be mirror images, and a maximum of 11 times if (1|1) is also included.




    Conclusion




    Either way, 12 (or 13) trumps 11 (or 4), so the analog clock wins.







    share|improve this answer



























      up vote
      0
      down vote













      Analog clock matches are:




      One math per hour (0 to 11 inclusively) = 12 matches
      An additional match at 6:00 = 1 match
      Those matches occurs twice per day since the hour handle makes 2 complete turns by day.
      (12 + 1) × 2 = 26 matches.




      For the digital clock we have:




      The following symmetries : 0 <--> 0, 1 <--> 1, 2 <--> 5 and 8 <--> 8
      Starting at midnight, we have:
      Leading 0: 00:00, 01:10, 02:50, 05:20 = 4 matches
      Leading 1: 10:01, 11:11, 12:50, 15:20 = 4 matches
      Leading 2: 20:05, 21:15, 22:55 = 3 matches
      Leading 5: No matches
      Leading 8: No matches
      Thus we have 11 matches per day




      So the result is:




      The analog clock matches more often.






      share








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        4 Answers
        4






        active

        oldest

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        4 Answers
        4






        active

        oldest

        votes









        active

        oldest

        votes






        active

        oldest

        votes








        up vote
        2
        down vote













        The times where the analog clock will match are




        The same as the times that the analog clock has reflective symmetry across it's "y" axis. This will happen at least once an hour. The proof for this involves the Intermediate Value Theorem, but essentially boils down to the fact that, every hour, the hour hand continuously sweeps one part of the clock, while the minute hand continuously sweeps the entire clock. It follows that, in sweeping the entire clock, it must for an instant pass through the part of the clock that is currently opposite the hour hand.


        It actually matches slightly more often than this, because they're already matching at noon/midnight, so it comes out to 13 matches every 12 hours, or 26 total.




        The times where the digital clocks will match are




        Again, where the clock has reflective symmetry across it's "y" axis (The colon). As @Dorrulf has already enumerated, this happens at 00:00, 02:50, 20:05, and 22:55. I'm not counting the times with ones in them, because they don't show up on the same half of the digit when reflected. This is a measly 4 total




        So, it's clear that the reflections match more often for the




        Analog Clock







        share|improve this answer
























          up vote
          2
          down vote













          The times where the analog clock will match are




          The same as the times that the analog clock has reflective symmetry across it's "y" axis. This will happen at least once an hour. The proof for this involves the Intermediate Value Theorem, but essentially boils down to the fact that, every hour, the hour hand continuously sweeps one part of the clock, while the minute hand continuously sweeps the entire clock. It follows that, in sweeping the entire clock, it must for an instant pass through the part of the clock that is currently opposite the hour hand.


          It actually matches slightly more often than this, because they're already matching at noon/midnight, so it comes out to 13 matches every 12 hours, or 26 total.




          The times where the digital clocks will match are




          Again, where the clock has reflective symmetry across it's "y" axis (The colon). As @Dorrulf has already enumerated, this happens at 00:00, 02:50, 20:05, and 22:55. I'm not counting the times with ones in them, because they don't show up on the same half of the digit when reflected. This is a measly 4 total




          So, it's clear that the reflections match more often for the




          Analog Clock







          share|improve this answer






















            up vote
            2
            down vote










            up vote
            2
            down vote









            The times where the analog clock will match are




            The same as the times that the analog clock has reflective symmetry across it's "y" axis. This will happen at least once an hour. The proof for this involves the Intermediate Value Theorem, but essentially boils down to the fact that, every hour, the hour hand continuously sweeps one part of the clock, while the minute hand continuously sweeps the entire clock. It follows that, in sweeping the entire clock, it must for an instant pass through the part of the clock that is currently opposite the hour hand.


            It actually matches slightly more often than this, because they're already matching at noon/midnight, so it comes out to 13 matches every 12 hours, or 26 total.




            The times where the digital clocks will match are




            Again, where the clock has reflective symmetry across it's "y" axis (The colon). As @Dorrulf has already enumerated, this happens at 00:00, 02:50, 20:05, and 22:55. I'm not counting the times with ones in them, because they don't show up on the same half of the digit when reflected. This is a measly 4 total




            So, it's clear that the reflections match more often for the




            Analog Clock







            share|improve this answer












            The times where the analog clock will match are




            The same as the times that the analog clock has reflective symmetry across it's "y" axis. This will happen at least once an hour. The proof for this involves the Intermediate Value Theorem, but essentially boils down to the fact that, every hour, the hour hand continuously sweeps one part of the clock, while the minute hand continuously sweeps the entire clock. It follows that, in sweeping the entire clock, it must for an instant pass through the part of the clock that is currently opposite the hour hand.


            It actually matches slightly more often than this, because they're already matching at noon/midnight, so it comes out to 13 matches every 12 hours, or 26 total.




            The times where the digital clocks will match are




            Again, where the clock has reflective symmetry across it's "y" axis (The colon). As @Dorrulf has already enumerated, this happens at 00:00, 02:50, 20:05, and 22:55. I'm not counting the times with ones in them, because they don't show up on the same half of the digit when reflected. This is a measly 4 total




            So, it's clear that the reflections match more often for the




            Analog Clock








            share|improve this answer












            share|improve this answer



            share|improve this answer










            answered 1 hour ago









            DqwertyC

            5,6571242




            5,6571242




















                up vote
                0
                down vote













                Last try...




                As a forward, I'm going more for the idea that the clocks read identical times rather than they just look similar.
                The only analog positions I see matching would be at 12:30 and 3:45, and their self-reflections (6:00 and 9:15) for a total of 8 occurrences in 24-hr a day. (Thanks @ExcitedRaichu)

                The digital clock has a few things of note beforehand:

                The leading 0's and set to military time.

                Again, if we function with the idea that as long as the times read the same (and the positions don't have to be exact - left oriented 1 versus right oriented 1), then we have these reflective cases: 0 to 0, 1 to 1, 2 to 5, 5 to 2. We can't use 8 because minutes only goes to 60. This gives us the following combinations (barring any were missed): 01:10, 11:11, 10:01, 15:21, 12:51, 05:20, 02:50. @DqwertC also found: 00:00, 02:50, 20:05, and 22:55.

                That puts us at a ration of 8:11, in favor of the digital clock.







                share|improve this answer






















                • I'm still unsure of my understanding of "reflective agreement" though xD
                  – Dorrulf
                  1 hour ago










                • doesn’t (rot13) fvkbpybpx work for analog as well?
                  – Excited Raichu
                  1 hour ago










                • Also, most digital clocks don’t have an 0 in front of the hour number if it’s one digit
                  – Excited Raichu
                  1 hour ago











                • @ExcitedRaichu It explicitly says they do in the problem.
                  – DqwertyC
                  1 hour ago










                • @DqwertC whoops. missed that.
                  – Excited Raichu
                  1 hour ago














                up vote
                0
                down vote













                Last try...




                As a forward, I'm going more for the idea that the clocks read identical times rather than they just look similar.
                The only analog positions I see matching would be at 12:30 and 3:45, and their self-reflections (6:00 and 9:15) for a total of 8 occurrences in 24-hr a day. (Thanks @ExcitedRaichu)

                The digital clock has a few things of note beforehand:

                The leading 0's and set to military time.

                Again, if we function with the idea that as long as the times read the same (and the positions don't have to be exact - left oriented 1 versus right oriented 1), then we have these reflective cases: 0 to 0, 1 to 1, 2 to 5, 5 to 2. We can't use 8 because minutes only goes to 60. This gives us the following combinations (barring any were missed): 01:10, 11:11, 10:01, 15:21, 12:51, 05:20, 02:50. @DqwertC also found: 00:00, 02:50, 20:05, and 22:55.

                That puts us at a ration of 8:11, in favor of the digital clock.







                share|improve this answer






















                • I'm still unsure of my understanding of "reflective agreement" though xD
                  – Dorrulf
                  1 hour ago










                • doesn’t (rot13) fvkbpybpx work for analog as well?
                  – Excited Raichu
                  1 hour ago










                • Also, most digital clocks don’t have an 0 in front of the hour number if it’s one digit
                  – Excited Raichu
                  1 hour ago











                • @ExcitedRaichu It explicitly says they do in the problem.
                  – DqwertyC
                  1 hour ago










                • @DqwertC whoops. missed that.
                  – Excited Raichu
                  1 hour ago












                up vote
                0
                down vote










                up vote
                0
                down vote









                Last try...




                As a forward, I'm going more for the idea that the clocks read identical times rather than they just look similar.
                The only analog positions I see matching would be at 12:30 and 3:45, and their self-reflections (6:00 and 9:15) for a total of 8 occurrences in 24-hr a day. (Thanks @ExcitedRaichu)

                The digital clock has a few things of note beforehand:

                The leading 0's and set to military time.

                Again, if we function with the idea that as long as the times read the same (and the positions don't have to be exact - left oriented 1 versus right oriented 1), then we have these reflective cases: 0 to 0, 1 to 1, 2 to 5, 5 to 2. We can't use 8 because minutes only goes to 60. This gives us the following combinations (barring any were missed): 01:10, 11:11, 10:01, 15:21, 12:51, 05:20, 02:50. @DqwertC also found: 00:00, 02:50, 20:05, and 22:55.

                That puts us at a ration of 8:11, in favor of the digital clock.







                share|improve this answer














                Last try...




                As a forward, I'm going more for the idea that the clocks read identical times rather than they just look similar.
                The only analog positions I see matching would be at 12:30 and 3:45, and their self-reflections (6:00 and 9:15) for a total of 8 occurrences in 24-hr a day. (Thanks @ExcitedRaichu)

                The digital clock has a few things of note beforehand:

                The leading 0's and set to military time.

                Again, if we function with the idea that as long as the times read the same (and the positions don't have to be exact - left oriented 1 versus right oriented 1), then we have these reflective cases: 0 to 0, 1 to 1, 2 to 5, 5 to 2. We can't use 8 because minutes only goes to 60. This gives us the following combinations (barring any were missed): 01:10, 11:11, 10:01, 15:21, 12:51, 05:20, 02:50. @DqwertC also found: 00:00, 02:50, 20:05, and 22:55.

                That puts us at a ration of 8:11, in favor of the digital clock.








                share|improve this answer














                share|improve this answer



                share|improve this answer








                edited 1 hour ago

























                answered 1 hour ago









                Dorrulf

                4265




                4265











                • I'm still unsure of my understanding of "reflective agreement" though xD
                  – Dorrulf
                  1 hour ago










                • doesn’t (rot13) fvkbpybpx work for analog as well?
                  – Excited Raichu
                  1 hour ago










                • Also, most digital clocks don’t have an 0 in front of the hour number if it’s one digit
                  – Excited Raichu
                  1 hour ago











                • @ExcitedRaichu It explicitly says they do in the problem.
                  – DqwertyC
                  1 hour ago










                • @DqwertC whoops. missed that.
                  – Excited Raichu
                  1 hour ago
















                • I'm still unsure of my understanding of "reflective agreement" though xD
                  – Dorrulf
                  1 hour ago










                • doesn’t (rot13) fvkbpybpx work for analog as well?
                  – Excited Raichu
                  1 hour ago










                • Also, most digital clocks don’t have an 0 in front of the hour number if it’s one digit
                  – Excited Raichu
                  1 hour ago











                • @ExcitedRaichu It explicitly says they do in the problem.
                  – DqwertyC
                  1 hour ago










                • @DqwertC whoops. missed that.
                  – Excited Raichu
                  1 hour ago















                I'm still unsure of my understanding of "reflective agreement" though xD
                – Dorrulf
                1 hour ago




                I'm still unsure of my understanding of "reflective agreement" though xD
                – Dorrulf
                1 hour ago












                doesn’t (rot13) fvkbpybpx work for analog as well?
                – Excited Raichu
                1 hour ago




                doesn’t (rot13) fvkbpybpx work for analog as well?
                – Excited Raichu
                1 hour ago












                Also, most digital clocks don’t have an 0 in front of the hour number if it’s one digit
                – Excited Raichu
                1 hour ago





                Also, most digital clocks don’t have an 0 in front of the hour number if it’s one digit
                – Excited Raichu
                1 hour ago













                @ExcitedRaichu It explicitly says they do in the problem.
                – DqwertyC
                1 hour ago




                @ExcitedRaichu It explicitly says they do in the problem.
                – DqwertyC
                1 hour ago












                @DqwertC whoops. missed that.
                – Excited Raichu
                1 hour ago




                @DqwertC whoops. missed that.
                – Excited Raichu
                1 hour ago










                up vote
                0
                down vote













                Assuming 'agrees with' is synonymous with 'looks the same'...



                Analog




                As suggested by DqwertyC, the analogue clock will agree 26 times in 24 hours if you include both mid-nights. If you argue that there is only one midnight in a 24 hour day then this can be reduced to 25 times. Assuming the latter these times are approximately: 00:55, 1:50, 2:46, 3:41, 4:37, 5:32, 6:28, 7:22, 8:18, 9:14, 10:09, 11:04, and 12:00 plus the equivalent times in the afternoon.




                Digital




                As suggested by Dorrulf and DqwertyC there are a minimum of 4 times when the digital clocks agree (if only (2|5), and (0|0) digits are considered to be mirror images, and a maximum of 11 times if (1|1) is also included.




                Conclusion




                Either way, 12 (or 13) trumps 11 (or 4), so the analog clock wins.







                share|improve this answer
























                  up vote
                  0
                  down vote













                  Assuming 'agrees with' is synonymous with 'looks the same'...



                  Analog




                  As suggested by DqwertyC, the analogue clock will agree 26 times in 24 hours if you include both mid-nights. If you argue that there is only one midnight in a 24 hour day then this can be reduced to 25 times. Assuming the latter these times are approximately: 00:55, 1:50, 2:46, 3:41, 4:37, 5:32, 6:28, 7:22, 8:18, 9:14, 10:09, 11:04, and 12:00 plus the equivalent times in the afternoon.




                  Digital




                  As suggested by Dorrulf and DqwertyC there are a minimum of 4 times when the digital clocks agree (if only (2|5), and (0|0) digits are considered to be mirror images, and a maximum of 11 times if (1|1) is also included.




                  Conclusion




                  Either way, 12 (or 13) trumps 11 (or 4), so the analog clock wins.







                  share|improve this answer






















                    up vote
                    0
                    down vote










                    up vote
                    0
                    down vote









                    Assuming 'agrees with' is synonymous with 'looks the same'...



                    Analog




                    As suggested by DqwertyC, the analogue clock will agree 26 times in 24 hours if you include both mid-nights. If you argue that there is only one midnight in a 24 hour day then this can be reduced to 25 times. Assuming the latter these times are approximately: 00:55, 1:50, 2:46, 3:41, 4:37, 5:32, 6:28, 7:22, 8:18, 9:14, 10:09, 11:04, and 12:00 plus the equivalent times in the afternoon.




                    Digital




                    As suggested by Dorrulf and DqwertyC there are a minimum of 4 times when the digital clocks agree (if only (2|5), and (0|0) digits are considered to be mirror images, and a maximum of 11 times if (1|1) is also included.




                    Conclusion




                    Either way, 12 (or 13) trumps 11 (or 4), so the analog clock wins.







                    share|improve this answer












                    Assuming 'agrees with' is synonymous with 'looks the same'...



                    Analog




                    As suggested by DqwertyC, the analogue clock will agree 26 times in 24 hours if you include both mid-nights. If you argue that there is only one midnight in a 24 hour day then this can be reduced to 25 times. Assuming the latter these times are approximately: 00:55, 1:50, 2:46, 3:41, 4:37, 5:32, 6:28, 7:22, 8:18, 9:14, 10:09, 11:04, and 12:00 plus the equivalent times in the afternoon.




                    Digital




                    As suggested by Dorrulf and DqwertyC there are a minimum of 4 times when the digital clocks agree (if only (2|5), and (0|0) digits are considered to be mirror images, and a maximum of 11 times if (1|1) is also included.




                    Conclusion




                    Either way, 12 (or 13) trumps 11 (or 4), so the analog clock wins.








                    share|improve this answer












                    share|improve this answer



                    share|improve this answer










                    answered 35 mins ago









                    Penguino

                    6,7921866




                    6,7921866




















                        up vote
                        0
                        down vote













                        Analog clock matches are:




                        One math per hour (0 to 11 inclusively) = 12 matches
                        An additional match at 6:00 = 1 match
                        Those matches occurs twice per day since the hour handle makes 2 complete turns by day.
                        (12 + 1) × 2 = 26 matches.




                        For the digital clock we have:




                        The following symmetries : 0 <--> 0, 1 <--> 1, 2 <--> 5 and 8 <--> 8
                        Starting at midnight, we have:
                        Leading 0: 00:00, 01:10, 02:50, 05:20 = 4 matches
                        Leading 1: 10:01, 11:11, 12:50, 15:20 = 4 matches
                        Leading 2: 20:05, 21:15, 22:55 = 3 matches
                        Leading 5: No matches
                        Leading 8: No matches
                        Thus we have 11 matches per day




                        So the result is:




                        The analog clock matches more often.






                        share








                        New contributor




                        Phil1970 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                        Check out our Code of Conduct.





















                          up vote
                          0
                          down vote













                          Analog clock matches are:




                          One math per hour (0 to 11 inclusively) = 12 matches
                          An additional match at 6:00 = 1 match
                          Those matches occurs twice per day since the hour handle makes 2 complete turns by day.
                          (12 + 1) × 2 = 26 matches.




                          For the digital clock we have:




                          The following symmetries : 0 <--> 0, 1 <--> 1, 2 <--> 5 and 8 <--> 8
                          Starting at midnight, we have:
                          Leading 0: 00:00, 01:10, 02:50, 05:20 = 4 matches
                          Leading 1: 10:01, 11:11, 12:50, 15:20 = 4 matches
                          Leading 2: 20:05, 21:15, 22:55 = 3 matches
                          Leading 5: No matches
                          Leading 8: No matches
                          Thus we have 11 matches per day




                          So the result is:




                          The analog clock matches more often.






                          share








                          New contributor




                          Phil1970 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                          Check out our Code of Conduct.



















                            up vote
                            0
                            down vote










                            up vote
                            0
                            down vote









                            Analog clock matches are:




                            One math per hour (0 to 11 inclusively) = 12 matches
                            An additional match at 6:00 = 1 match
                            Those matches occurs twice per day since the hour handle makes 2 complete turns by day.
                            (12 + 1) × 2 = 26 matches.




                            For the digital clock we have:




                            The following symmetries : 0 <--> 0, 1 <--> 1, 2 <--> 5 and 8 <--> 8
                            Starting at midnight, we have:
                            Leading 0: 00:00, 01:10, 02:50, 05:20 = 4 matches
                            Leading 1: 10:01, 11:11, 12:50, 15:20 = 4 matches
                            Leading 2: 20:05, 21:15, 22:55 = 3 matches
                            Leading 5: No matches
                            Leading 8: No matches
                            Thus we have 11 matches per day




                            So the result is:




                            The analog clock matches more often.






                            share








                            New contributor




                            Phil1970 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                            Check out our Code of Conduct.









                            Analog clock matches are:




                            One math per hour (0 to 11 inclusively) = 12 matches
                            An additional match at 6:00 = 1 match
                            Those matches occurs twice per day since the hour handle makes 2 complete turns by day.
                            (12 + 1) × 2 = 26 matches.




                            For the digital clock we have:




                            The following symmetries : 0 <--> 0, 1 <--> 1, 2 <--> 5 and 8 <--> 8
                            Starting at midnight, we have:
                            Leading 0: 00:00, 01:10, 02:50, 05:20 = 4 matches
                            Leading 1: 10:01, 11:11, 12:50, 15:20 = 4 matches
                            Leading 2: 20:05, 21:15, 22:55 = 3 matches
                            Leading 5: No matches
                            Leading 8: No matches
                            Thus we have 11 matches per day




                            So the result is:




                            The analog clock matches more often.







                            share








                            New contributor




                            Phil1970 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                            Check out our Code of Conduct.








                            share


                            share






                            New contributor




                            Phil1970 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                            Check out our Code of Conduct.









                            answered 6 mins ago









                            Phil1970

                            1992




                            1992




                            New contributor




                            Phil1970 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                            Check out our Code of Conduct.





                            New contributor





                            Phil1970 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                            Check out our Code of Conduct.






                            Phil1970 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                            Check out our Code of Conduct.



























                                 

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