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Rare Rotative Relationship! (Posted on 2004-09-23) Difficulty: 3 of 5
What is the smallest number so that if you move its last digit to the beginning (for example, turning 1234 into 4123) you get a new number that is an integer multiple of the original number?

  Submitted by Old Original Oskar!    
Rating: 4.7500 (4 votes)
Solution: (Hide)
Suppose the number is abc...z. Let's write N=0.abc...zabc...z.... Therefore, (N+z)/10=0.zabc...zabc...z.... We want this to equal KN, with K an (unknown) integer, 10>K>1. (If K≥10, KN would have more digits than K.)

If (N+z)/10=KN, then N=z/(10K-1). As a≥1, then z≥K. So, if we study z/(10K-1) for 10>K>1, z≥K, and look for the smallest abc...z, we'll have the answer.

For K=z=4 we produce N=0.102564102564... so the answer is 102564.

Comments: ( You must be logged in to post comments.)
  Subject Author Date
SolutionPuzzle Solution With ExplanationK Sengupta2007-06-07 05:34:24
AnswerK Sengupta2007-06-07 05:14:55
SolutionFull Algebraic SolutionCandide2004-09-28 17:04:01
The algebraic wayJer2004-09-27 13:11:37
Some Thoughtsre: Another ideaOld Original Oskar!2004-09-27 12:20:30
Another ideaGamer2004-09-26 11:01:05
No Subjectabhi ghosh2004-09-26 07:28:54
re(2): Solutions with interpretationsRichard2004-09-24 00:47:05
re: Solutions with interpretationsNosher2004-09-23 21:47:29
re: Solutions with interpretationsDavid Shin2004-09-23 19:06:04
SolutionThe first fewCharlie2004-09-23 13:27:56
Solutions with interpretationsJer2004-09-23 13:16:29
SolutionSolutionDavid Shin2004-09-23 13:07:08
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