Sunday, December 13, 2009


NPR Sunday Puzzle Plus

The NPR Sunday Puzzle this week was a fun one to solve.
Name five two-digit numbers that are evenly spaced out — like 32, 34, 36, 38 and 40 — in which all 10 digits from 0 to 9 are used once each. What numbers are these?
I overheard it while trying to get back to sleep. Drifting in and out of consciousness I figured it out in about 10 minutes. For fun (seriously), I coded a solution to the problem. It turns out there are 4 correct answers, all of which begin or end with a multiple of 10.

Then I figured out the same thing for 5 four digit numbers in which the digits from 0 to 9 appear twice. I found 618 solutions. My favorites used 1111 as the increment, three of which contained the solution to the first puzzle.

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