Counting to 50
Logic puzzles require you to think. You will have to be logical in your reasoning.
Henry and Gretchen are going to play a game. Henry explains, "You and I will take turns saying numbers. The first person will say a number between 1 and 10. Then the other person will say a number that is at least 1 higher than that number, and at most 10 higher. We will keep going back and forth in this way until one of us says the number 50. That person wins. I'll start."
"Not so fast!" says Gretchen. "I want to win, so I will start."
What number should Gretchen say to start?
HintBy following this strategy, she is assured a victory. Think of all of the numbers she will want to say.
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Answer
She wants to say, "6."
The series of numbers she will say is 6, 17, 28, 39, 50.
Since she wants to say 50, she needs Henry to say a number between 40 and 49. Therefore, she wants to say 39.
Knowing she wants to say 39, she needs Henry to say a number between 29 and 38. So she wants to say 28. Following this same logic recursively, she will want to say 17, and she will want to say 6 to start the game, and be assured victory.
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Comments
(user deleted)
Jan 11, 2005
| good one |
strangelove
Jan 12, 2005
| I really wanted to get this one and it took me some time. Excellent!! |
mosoh  
Jan 12, 2005
| Nice |
eina_23052  
Jan 13, 2005
| this was a 5 star teaser
|
God-sGrace2005 
Jan 13, 2005
| I like your teaser I saw something like that on tv once. |
(user deleted)
Jan 20, 2005
| isnt it possible to beat her if i say 15? |
tsimkin   
Jan 20, 2005
| no. if you say 15, she will say 17. then whatever you say, she will be able to say 28. then whatever you say, she will be able to say 39. then whatever you say, she will be able to say 50, and win. |
i_am_sam007
Jan 23, 2005
| I liked it, but it was a bit easy. I play these kinds of games all the time. Kepp up the great teasers. |
(user deleted)
Jan 26, 2005
| I used to play a game like this called "21." We could say 3 numbers at a time and the first one to say 21 loses.
I like this teaser! This one is definetly going into my Favorites!  |
RoxyChick13  
Jan 27, 2005
| CUTE!!  |
chuckelect 
Feb 09, 2005
| one of my favorites, great job. |
roseblood003  
Feb 11, 2005
| U sure stumped me! Nice one!  |
horseybaby34345  
Feb 11, 2005
| I LOVED IT!!!!
i wuz stumped until i read the hint
make sum mor!!
 |
94_8  
Feb 11, 2005
| wonderful  |
fuzzie277
Feb 11, 2005
| I suck at math, so I didn't get this. But I like this kind of puzzle, so:  |
marigold  
Feb 11, 2005
| I don't know about everone else, but that teaser was really hard for me. I'm not too great with numbers... Anyway, great teaser!  |
(user deleted)
Feb 12, 2005
| new to this site...enjoy it very much....nice teaser,albeit just a tad easy...good though...thats the thing with math...the numbers never lie...keep 'em coming... |
melilyn 
Feb 12, 2005
| I've played the 21 game too, but you WIN if you get to 21... very nice, though, finally a tough one! |
Raza
Feb 13, 2005
| I liked this one and was able to solve it easily . |
dogfanatic77
Feb 13, 2005
| awesome! i'm gonna play that game now, cause i'm sure to win!! keep up the good work!!  |
itsn06
Feb 15, 2005
| Good job! One thing though: The words "at least" leave too many possibilities. It could have worked out differently. |
tsimkin   
Feb 15, 2005
| Actually, the words "at least" do not leave too many possibilities. Whatever Henry says after Gretchen says "6", she will be able to say "17". For example, if he said, "12", she would say "17". Then whatever he said next (say, 19), she would say 28. If you disagree, send me a PM. Thanks. |
Tree  
Feb 24, 2005
| Very good teaser. I've never seen one like that. It reminds me of a game where you take away marbles in rows that I played recently.  |
jimmym  
Sep 10, 2005
| why not just say 50?  |
tsimkin   
Sep 12, 2005
| jimmym -- You don't just say 50 for the same reason that you don't play darts by walking up to the dart board to placing your darts all in the bull's-eye. The game has rules, and the object is to win it while still playing by the rules. "The first person will say a number between 1 and 10..." |
jsdodgers   
Sep 13, 2006
| Smart  |
calmsavior   
Sep 18, 2006
| i found it easy
no seriously |
kuttiekat2u
Jan 14, 2007
| how am i supposed to know????????????? |
kuttiekat2u
Jan 14, 2007
| just say 50 and you win |
bradon182001   
Sep 08, 2008
| Good thought provoking teaser. i didn't get it right either. Thanks for posting.  |
malogalee   
Sep 08, 2008
| i didnt even try! i like the answer of just say 50....lol |
auntiesis   
Sep 08, 2008
| That was easy, I started with 50 and worked backwards, just like the answer. It took me longer to figure it out than to read the answer and I needed paper & pen.  |
doehead   
Sep 08, 2008
| Very easy. 50-(11+1x4)=6  |
doehead   
Sep 08, 2008
| I meant 10+1x4  |
UptheHill  
Sep 08, 2008
| NICE!!! |
abrain  
Sep 08, 2008
| Tough but fair! Thanks  |
avonma   
Sep 08, 2008
| Great quiz!
But, I don't do numbers...  |
crystalblade 
Sep 08, 2008
| Like anybody would actually play that game in real life. |
dragonlove  
Sep 08, 2008
| Nice puzzle! I had to work it backwards also. :-) |
FatHead    
Sep 08, 2008
| What can I say? This was easy for me, a nim expert. |
srpwuzhere   
Sep 08, 2008
| hehe me and my friends used to play a game where you would have to count to 100. whoever got there was out and kept going until there was one person left. whoever was left wins :-)
good teaser btw! |
jentaylor728
Sep 08, 2008
| I disagree...
6, "and at most 10 higher" is 16
NOT 17...
Maybe I'm just tired but it doesn't make sense to me!
 |
BookwormAnG 
Sep 08, 2011
| Just say 50 Gretchen! |
HABS2933   
Sep 08, 2011
| That was my solution too BookWorm. Did the rules say we couldn't say 50 right off the bat? |
HABS2933   
Sep 08, 2011
| Opps nevermind, yes it did, you had to start with a number between 1 and 10.  |
doehead   
Sep 08, 2011
| AROB. Still easy  |
teri12265  
Sep 08, 2011
| Ok, if she says 10, then he says 11 − 20, then she can pick 21, he 22 − 31, her 32, him - 33 −42, her - either 39 or 50 depending on his pick.
Isn't this a possibility as well?
And doe - please translate arob???
(= |
tsimkin   
Sep 08, 2011
| Teri -- when you say that he can say 33-42, that means he can say 39. If he does, Gretchen is out of luck, since she will then have to say a number between 40 and 49. |
teri12265  
Sep 08, 2011
| guess I need more coffee! |
omas   
Sep 08, 2011
| great teaser. Something to amuse my kids!! |
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