AB. The Rational Ruler

October 9, 2005 · answers, Favorites, math puzzles, numbers, The Mathcast · Permalink

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Finer and finer, a ruler with infinitely many marks…

We answer last week’s puzzle, discuss rational and irrational numbers, and pose a little question about coins.

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4 Comments »

  1. Ben Weiss said,

    August 24, 2009 at 10:13 am

    Alternative solution to 12″ rod puzzle.
    1,2,6,9
    Ben Weiss (age 10)

  2. Daniel said,

    August 29, 2009 at 5:19 am

    I think I now have the complete list of solutions
    1,3,5,11
    1,3,7,11
    1,2,3,8
    1,2,6,9
    1,4,5,10
    1,4,7,10
    1,7,8,10

  3. Travis said,

    November 10, 2009 at 11:08 am

    I gave this problem to my Algebra I students.  They found 13 different solutions.
    1,2,3,8    1,2,6,9    1,3,5,11    1,3,7,11    1,4,5,10
    1,4,7,10    1,5,9,11     1,7,8,10    1,7,9,11
    2,4,5,11    2,5,8,11    3,6,10,11    4,9,10,11
     

  4. Daniel said,

    November 13, 2009 at 8:48 am

    Yes, but some of these are duplicates.  For example, 4,9,10,11 is the same as 1,2,3,8 and 1,5,9,11 is the same as 1,3,7,11.

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