SOLUTION: David wants to arrange the twelve numbers from 1 to 12 in a circle so that any two neighbouring numbers differ by either 2 or 3. Which of the following pairs of numbers have to b

Question 1070705: David wants to arrange the twelve numbers from 1 to 12 in a circle so that any two
neighbouring numbers differ by either 2 or 3. Which of the following pairs of numbers have to
be neighbours?
(A) 5 and 8 (B) 3 and 5 (C) 7 and 9 (D) 6 and 8 (E) 4 and 6
Answer by Edwin McCravy(20060) (Show Source): You can put this solution on YOUR website!

I've only found one way to make such a circle, other
than to rotate it and/or reverse it:

             1
         4      3
       2          6
      5            8
       7          11
        10       9
            12

It has 6 and 8 as neighbors, but none of the others.

So the correct choice, if it can be one of those, it 
can only be (D)

Edwin

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