IBM Research | Ponder This | July 1999 challenges

Ponder This

July 1999

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Ponder This Challenge:

 While bowling, you notice that the ten pins (arranged in a triangle) are labeled with the different integers 0,1,...,9, and that if two pins are side-by-side, the sum of their labels (reduced modulo 10) is equal to the label of the pin in front and between them. For example:             1    2    4    5                3    6    9                  9    5                     4 Add the labels of the two pins in the second row to obtain the label of the one pin in the first row: (9+5=14 = 4 mod 10). But in the example some of the pins have the same label; in the solution, they don't. While you are busy noticing this, your opponent makes a strike. How are the pins labeled?

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Challenge: 07/01/99 @ 12:00 AM EST
Solution: 08/01/99 @ 12:00 AM EST
List Updated: 08/01/99 @ 12:00 AM EST