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Friday, March 17, 2017

Fun Math puzzle

Find 2 consecutive integers such that, the sum of the digits of the first number is divisible by 7.  And so is the second number.

5 comments:

  1. 34 and 35! I wrote a program to calculate this after reading the puzzle, thinking the answers would be much higher. Needless to say, I had fun solving it!

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  2. This is also true of
    160, 161
    167, 168
    223, 224
    293, 294
    412, 413
    419, 420
    And many, many more

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  3. Another interesting finding is that the first occurrence where BOTH integers have a sum of digits that's divisible by 7 happens at (69999,70000) and not again until (159999, 160000)

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  4. In fact, in the first 1 million integers, there are 20411 sequential integer pairs that meet the criteria of the initial puzzle!

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  5. In the first BILLION integers? 20,408,136 sequential pairs meet the criteria!

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