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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.


  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!

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

  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)

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

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