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Guest Message by DevFuse

# order of the cards

Best Answer m00li, 21 April 2014 - 03:13 PM

5 + 5! = 125

Suuppose you chose the following cards [generated randomly]:

103

89

86

46

54

74

which card would you keep and how would your friend know the identitiy of the one you kept?

Spoiler for explanation
Go to the full post

8 replies to this topic

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Posted 15 April 2014 - 10:26 PM

You and your friend are told that there are N cards, each are numbered from 1 to N. You will randomly select 6 cards. Using the perfect coding system which you had set with your friend previously, you will select one card and transfer the other five to your friend. By just examining the order of these numbered five cards, your friend will be able to know the card youve selected.

What can be the maximum value for N?
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### #2 bonanova

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Posted 16 April 2014 - 01:28 AM

Spoiler for clarification
Spoiler for also

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The greatest challenge to any thinker is stating the problem in a way that will allow a solution.
- Bertrand Russell

### #3 m00li

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Posted 21 April 2014 - 05:37 AM

5 + 5! = 125

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### #4 dgreening

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Posted 21 April 2014 - 01:32 PM

5 + 5! = 125

Suuppose you chose the following cards [generated randomly]:

103

89

86

46

54

74

which card would you keep and how would your friend know the identitiy of the one you kept?

• 0

### #5 m00li

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Posted 21 April 2014 - 03:13 PM   Best Answer

5 + 5! = 125

Suuppose you chose the following cards [generated randomly]:

103

89

86

46

54

74

which card would you keep and how would your friend know the identitiy of the one you kept?

Spoiler for explanation

• 0

### #6 dgreening

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Posted 21 April 2014 - 05:13 PM

Very clever aproach m00li!! I like it!

Spoiler for I think there is a way to extend this approach significantly

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### #7 m00li

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Posted 21 April 2014 - 05:44 PM

Very clever aproach m00li!! I like it!

Spoiler for I think there is a way to extend this approach significantly

Very nice indeed!

But the poster (or is it poser) has mentioned that " By just examining the order of these numbered five cards, your friend will be able to know the card youve selected."

I think we cannot use any other hints but just the order. (e.g. you can increase binary to ternary by handing some cards with your left. So an extra dimension is added by virtue of whether you touched a card with your left hand or right).

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### #8 dgreening

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Posted 21 April 2014 - 07:42 PM

Good point!

I think you are probably correct ... oh well. I still think yours is a really good approach!

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Posted 22 April 2014 - 03:07 AM

Mooli found the answer I was looking for.  Well done!

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