A party is being held at a local mansion. The host is very rich and his success is because of one thing — his famous recipe for spaghetti!

The only guests that may attend are people who correctly reply to the guard at the door.

Here's where you come in. You and a friend are trying to steal this recipe. You sneak by and listen to the passwords.

The first guest arrives. The security says "2", and the guest replies "2".

The second guest arrives. The security says "4", the guest replies "4".

Your friend thinks he's got it all figured out (again), so he walks up to the door and the security says "6". He replies "6", and is trampled to death by elephants.

Another guest arrives, security says "3" and the guest replies "2" to get in.

You walk up and get a "5" from security. What is your response?

The correct answer has already been given, but the method hasn't been guessed. So here's a hint:

challenge response
1 0
2 2
3 2
4 4
5 4
6 4

And here is another hint: "Petals Around the Rose" (although it's not that).


It's the number of pips in the corners of that face of a standard six-sided die.

  • $\begingroup$ I knew as soon as I saw the hint that it was this answer. $\endgroup$
    – user88
    Nov 16 '14 at 23:41
  • $\begingroup$ @Joez Yeah, the hint is what got it for me too. $\endgroup$
    – xnor
    Nov 16 '14 at 23:48

Update: This is a now outdated answer to the original version of the puzzle. The presented solution does no longer match the current formulation.

I'd guess the solution is

4, i.e. the largest power of 2 not above the number said by the security.

But I'm just too afraid of those damn elephants :-D

  • 1
    $\begingroup$ Correct answer, wrong method. $\endgroup$
    – SQB
    Nov 11 '14 at 11:22
  • 2
    $\begingroup$ @SQB That says more about the question than about the answer. $\endgroup$ Nov 11 '14 at 14:50
  • 1
    $\begingroup$ That wouldn't work, because then the correct answer to "1" would be "1". $\endgroup$ Nov 15 '14 at 22:35
  • $\begingroup$ @randal'thor Thanks, I didn't notice the edits to the question. $\endgroup$
    – GOTO 0
    Nov 16 '14 at 10:09

2 and 3 answer is 2, 4 and 5's answer is 4, so for 6 it would've been 7 I think

The answer is already out there, I am just trying to figure out a correct method.

  • $\begingroup$ By extension of your logic (2 = 2/3, 4 = 4/5) the answers for 6 should be 6/7, but we know that 6 isn't a valid answer to 6 $\endgroup$
    – Joe
    Nov 11 '14 at 11:47

The answer is:

4 because is the highest even number that can be divided from the number given by the guard, not counting the reminder obviously!

  • 1
    $\begingroup$ "divided not counting the remainder" makes no sense. Divisibility implies the remainder is zero. $\endgroup$
    – apnorton
    Nov 11 '14 at 17:09

so the question is 2=2, 4=4, 6=/=6, 3=2, 5=?

so every answer is even number and must less than 5 (because 6 =/= 6)
if the question is given odd number, it should minus 1 (so that 3-1=2)
so that answer is 5-1=4, about the poor friend, his answer should be 6-4=2


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