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My favorite number (Posted on 2003-06-16) Difficulty: 2 of 5
You are trying to guess my favorite number. I tell you it is from 1-100 somewhere and is an interger. You can guess anything you like and I will tell you whether my number is higher or lower then your guess. What is the smallest number of guesses you can make to make sure you will get my number, no matter what it is?

Assume that I don't lie to you about the greater or less than value.

  Submitted by Jon    
Rating: 2.6667 (6 votes)
Solution: (Hide)
The logic to this game starts by going half way between the limits you know for the number. The first logical guess would be 50. Say my number is 17. So the guesser would say 50(1 guess), and I would say lower. G(short for guesser)=25(2), me=lower. G=12(3), me=higher. G=19(4), me=lower. G=16(5) me= higher. G=18(6), me=lower. G=17(7), I say right. 7 is the least number of guesses required to guess any number. Obviously you can get lucky, but this way works better most of the time. This is also proved by using powers of 2. 2^1=2 2^2=4 ....... 2^6=64 2^7=128 this means that these same 7 guesses could be used for every number between 128 and 1. I like 1-100 better.

Comments: ( You must be logged in to post comments.)
  Subject Author Date
SolutionSolutionDej Mar2008-06-17 04:59:10
answerK Sengupta2007-11-12 02:29:00
re: The Trick (Full Solution)Ady TZIDON2006-01-18 10:18:11
re: Possible solution?Ady TZIDON2006-01-18 10:10:08
hopefully this site is so confusingViet2003-07-14 07:03:04
Some Thoughtsre: Is this right?DJ2003-06-19 16:53:58
So hardriddler2003-06-19 12:21:28
Some ThoughtsIs this right?Gamer2003-06-19 05:54:07
re: The Trick (Full Solution)Gamer2003-06-19 05:45:47
SolutionThe Trick (Full Solution)DJ2003-06-17 17:24:10
Some Halve it, some don'tSanjay2003-06-16 09:46:30
My waynot_so_einstein2003-06-16 07:31:26
re(2): Possible solution?DJ2003-06-16 06:29:30
re: Possible solution?Gamer2003-06-16 05:57:42
SolutionPossible solution?fwaff2003-06-16 03:09:46
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