It’s the Friday Puzzle!

92

Take five matchsticks and form the figure of a giraffe as is shown in the diagram.  Now can you move just one matchstick so that the shape of the giraffe is remained intact but is rotated or reflected?

As ever, please do NOT post your answers, but do say if you think you have solved the puzzle and how long it took. Solution on Monday.

I have produced an ebook containing 101 of the previous Friday Puzzles! It is called PUZZLED and is available for theKindle (UK here and USA here) and on the iBookstore (UK here in the USAhere). You can try 101 of the puzzles for free here.

92 comments on “It’s the Friday Puzzle!

  1. AMWhy says:

    It took me about a minute of looking to come up with an answer, although the shape of mine isn’t exactly the same as the original…

    • Michael Sternberg says:

      I concur.

      And then there are some Picasso-style solutions.

    • Steve Jones says:

      I’d agree – the original isn’t drawn correctly to get a perfectly symmetrical result. So the short answer is “no”.

      Also, what’s with this ugly wording “the shape of the giraffe is remained intact”? Perhaps the imperfection of the grammar is reflective of that of the drawing.

    • Steve Jones says:

      nb. of course one thing that could be done is a minor movement of one matchstick and I can achieve an image that shows a reflection and rotation symmetry (in combination), albeit with a non-conventional axis…

    • Edgar 2 says:

      I don’t think you can – I think a second adjoining match would need to be rotated slightly as well.

  2. MatchstickCatsNdogs says:

    Took about 10 seconds, but my giraffe has a big waggly tail and is doing the splits.

  3. Roland says:

    The way Richard made the drawing it cannot be done. He made a “capital” error with the angle of one matches.

  4. Dan says:

    Took a couple of minutes but so obvious when you see it!

  5. It took me a few minutes before I wanted to admit it: the puzzle as it is, has no solution. It is wrong.

  6. Jaq says:

    This was an easy one, Richard.

  7. The Masked Twit says:

    I know that you are not meant to give spoilers, but the correct answer is No. It can’t be done properly.

  8. Simon says:

    I can do it – but I have a complaint – because of the way it has been drawn, the shape does change slightly.

  9. Brayden says:

    got it in about 20 seconds. it is possible!!

  10. The Quicker Fixer-Upper says:

    Hey Richard, use this image instead.

  11. Andrew says:

    I have a straightforward mathematical,proof that the answer to this puzzle is: No, you can’t.

    • The Quicker Fixer-Upper says:

      Don’t be so pedantic. Just because some of the angles aren’t exactly right doesn’t mean there’s no solution. I think we can all figure out what Richard intends here.

    • Anon says:

      Andrew is not being pedantic. We all have different ways of solving these problems. Looking at them from “different angles” if you will. The problem as stated can not be solved in one move. I do not for one minute suppose that Andrew can not see the quasi solution that Richard is angling for.

    • The problem with things like these is that you can’t know the correct answer. What seems like an obvious mistake, may very be intentional, and in that case, correcting the mistake may well turn out to be considered the wrong answer.

    • The problem with things like these is that you can’t know the correct answer. What seems like an obvious mistake, may very *well* be intentional, and in that case, correcting the mistake may well turn out to be considered the wrong answer.

  12. D says:

    Done. 10 seconds.😀

  13. Craig Morgan says:

    Yup, got this quickly, in about 20-30 seconds.

  14. dharmaruci says:

    richard has drawn a vampire giraffe. it has no reflection

  15. Matt says:

    Took a few minutes to get the solution but I’ll blame that on the wine.

  16. serolrom says:

    Not 10 seconds for me, but less than a minute.
    Yeah, guys, you are somehow right that the shape cannot remain 100% unchanged, but open your minds, Richard asks to copy this shape with matches, obviously the shape will never be perfect.
    Once done, there is still a giraffe, although “rotated or reflected”.

    • The Masked Twit says:

      OK.
      I can do it in two moves.
      Two is pretty much the same as one really. Is that open minded enough?

  17. The Quicker Fixer-Upper says:

    Just for fun, I’m pretending the matchsticks form a parasaurolophus. 😀

  18. Nanda gunawardhana says:

    good one …done in 30 seconds

  19. JP says:

    The homothety took 25 sec to reveal. Quite an elegant neck with as much vertebra as mine!

  20. I saw it after 30 seonds and then I was something like “Was I really so stupid for not seeing it?”

  21. Yat says:

    If the angles were right, maybe the symmetry would have been even more obvious…
    Note that the use of the term “intact” instead of “identical”, for example, is a way to allow the solution : the giraffe has just moved its neck and head…
    But is it ok to say that it has been rotated OR reflected, as we need both transformations ? In boolean logic, or would be ok, but in human language, or means xor, no ?

    • @techiebird says:

      I didn’t even notice the angle of the controversial match. I was completely thrown by the ‘or’.

      My solution is reflected AND rotated, so no, it can’t be kept intact and reflected OR rotated🙂

  22. Derby says:

    About 30 sec.nice, I will give it to my students.

  23. James says:

    Assuming I got it right, I saw it almost immediately…probably 10 seconds. Luck more than insight though!

  24. Jon says:

    Giraffe! That head is definitely the alien from Alien.

  25. Anonymous says:

    so easy that btec students got it in seconds!

  26. Puddleglumish says:

    We BTEC students say “so easy”.

  27. Charles White says:

    Got it in less than a minute.

  28. Berhard says:

    looked at it and the solution appeard in lets say 15 seconds…

  29. Chris says:

    i spent most of my time trying to see the giraffe in richard’s picture of a parasaurolophus.

  30. nainfort says:

    the irony ! you saved the gif1 file into jpeg format !

  31. Laura says:

    About two mins – inc drawing diagram – but I’ve seen things like this before and it’s a process of illimination

  32. Richard says:

    I think without the updated diagram I might have got the answer but then I would have thought “no, that’s wrong”. One of the first things I checked was whether the “head” was at a right angle to the “neck”, which it isn’t, and so in the state the puzzle is set, my solution would not have been valid.

  33. Eddie (@edzeteito) says:

    Got it. Quite clever. Nice one.

  34. lindamp says:

    “is remained”?? No!

  35. Peter S says:

    I can do it but got stuck for a while on the phrase “rotated or reflected”. Without giving spoilers, how pedantic should we be in these puzzles?

  36. W says:

    “Now can you move just one matchstick so that the shape of the giraffe is remained intact but is rotated or reflected?”

    In the spirit of the previous puzzle and without even looking into it I’d venture that that “No” is a valid answer

  37. Sari1967 says:

    Got it took about a minute like this one!

  38. Richard says:

    I think “or” can be taken to mean “and/or” rather than “xor”.

    If you had a son and a daughter, and someone asked you to give a yes/no answer to the question “do you have a son or a daughter?”, would you really answer “no”?

    • Anonymous says:

      If a yes/no answer is requested, I would obviously say yes… but what is the point of requesting a yes/no answer if the natural way to understand “or” was “and/or” rather than “xor” ?

      If no precision was made about the type of answer, I would naturally answer something like “both”, and I bet most people would too. Wouldn’t you ?

    • Richard says:

      The reason I specified a yes/no answer in the example is because we were talking about which type of “or” was specified – and both types only have those two values as possible results.

      You need a true/false value (ie a yes/no) to decide if your final answer has been “rotated or reflected”. There is no Boolean “both”.

    • Richard says:

      On further “reflection” (geddit?) I think it’s context-dependent. “Have you got a son or daughter?” looks like an and/or to me, but “you can have meat or potatoes” looks like exclusive or.

      I don’t know which it is in the context above, but funnily enough it doesn’t matter either.

    • Anonymous says:

      I disagree. If in the 40$ menu you see “cheese or pie”, that means you can’t have both. That’s what “or” means in the common language. You can have this or that, you need to chose. That’s why when you ask someone if he has a boy or a girl, I think a normal person who has both would answer “both” instead of “yes” or “no”.

      When the problem says the giraffe can be reflected or rotated, it would mean that it can’t be both reflected and rotated, because those puzzles here are usually loosely formulated and thus should be interpreted as natural language, not as formal mathematical statement. If it was, the meaning of “or” would be precised by adding “or both”, or “but not both” anyway.

      Of course this is totally moot because a combination of a reflection and a rotation is still a reflection (silly, silly me !), so in that case there is no problem, the giraffe is just reflected.

    • Yat says:

      “Have you a son or a daughter ?” looks like an and/or to you ? I would bet that if you ask that in written form to anyone who has both, without specifically requesting a yes/no answer, you would not get many “yes”. But I can’t be sure without trying… I have just tried here with two colleagues who I knew had both, but I obviously cheated, because in that case (and in my language), the way you ask it makes it really clear what you are asking. I did not think about that before trying orally.

  39. It is impossible with this drawing and, more importantly, that is CLEARLY an antelope.

  40. Edgar 2 says:

    Took about 30 secs to get “the” answer, then as much again to worry over the angle issue.

    As has already been said the question doesn’t say “identical”, it just says the shape “is remained intact ” (is that a typo for “retained”? – that’s my guess).

  41. Duncan says:

    I have a solution I’m not really happy with. I hope there’s a better one and I’ve missed something.

  42. To those worrying about rotated AND reflected. I seem to rememer that and combination of those two transformations can be expressed as a single reflection. I hope that’s oblique enough not to be a spoiler.

  43. Rob says:

    A bit less than a minute I guess although I did look and then get on with some work and come back to it so perhaps I background processed it! Also the head is at a slightly different angle … is that acceptable? Otherwise I don’t think it can be done.

  44. static1812 says:

    I moved on matchstick and it diffracted … so sad😦

  45. Mike Torr says:

    Isn’t it about time that Richard owned up to the true purpose of these Friday puzzles: to study the psychology of people’s replies? Why else would so many of them be either contentious or carelessly posed?😉

    • The Quicker Fixer-Upper says:

      The Richard Wiseman puzzles are an inside job!

    • michel amm says:

      Do you thing Richard is working for us for free ?

      Do you think think facebook is working for us for free ??

      Do you think think google is working for us for free ???

    • The other Matt says:

      I also thought about that. Its interesting to study the answers and the discussions, more tha tha puzzle.
      I think Richard wants just to entertain us, he does his job well. Its not easy to find puzzles they are not able to find in google. Sometimes i think some people just post the value of their search engine: …got it in 2 seconds…
      By the way: look at the banner right.
      I found this website when i was looking in youtube for card tricks and found the “colour canging card trick”, one of my most favourite ! So this combination of commerciel and fun will also bring customers.

  46. Mervulon says:

    I like turtles.

  47. Lazy T says:

    that’s a pic of a hut with me on top.

  48. bitterjoe says:

    About 15 seconds.

  49. Henry Ruddle says:

    I get the feeling that Richard is planning a new book of Puzzlers For Kids.

  50. Jenifer says:

    Got it. Took about a minute.🙂

  51. The Moon is a Harsh Mistress says:

    TANSTAAFL.

  52. Mort Canard says:

    Puzzled original giraffe is asking eager solution giraffe what all of the fuss is about regarding the minor difference in head inclination.

  53. John Loony says:

    These puzzles always used to be devious and difficult, with lots of variation possible according to the interpretation of the wording.

    Then, for the last three or four weeks, thay have all been very easy and obvious.

    Now, it’s back to the devious ones. I have got the answer, but only from reading all the clues in the comments first.

    The most important clue is from the Quick Fixer-Upper who provided a “corrected” version of the original drawing.

  54. Hayward Dennis says:

    Got it. About 10 seconds. I’m getting better a this!

  55. Lisa says:

    Got it. Several years. About time.

  56. Ronda says:

    Feeling totally stupid! It took me WAY too long. More than five minutes, and then…DOH!

  57. Tyesha says:

    Awfully illuminating thank you, I do think your current visitors may perhaps want a whole lot more information such as this continue the good effort.

  58. Anonymous says:

    I’m stuck.
    Answer please

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