It’s the Friday Puzzle!

64

You face a room of very hungry people.  A large pizza arrives and you are handed a knife and asked to cut the pizza into as many pieces as possible using just three straight cuts.  Because the pizza is very hot you cannot move any of the pieces (e.g. stacking them on top of one another and then cutting).  What is the maximum number of pieces that you can create using just three straight cuts?

As ever, please do NOT post your answers, but do feel free to say if you think you have solved it 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 the Kindle (UK here and USA here) and on the iBookstore (UK here in the USA here). You can try 101 of the puzzles for free here.

 

64 comments on “It’s the Friday Puzzle!

  1. Quadratic equation needed – nuf said …

  2. MarKill says:

    think I did LOL but I’m never sure till the answer arrives

  3. z says:

    Immediate.

  4. M says:

    I think I got it.

    Will check again later.

  5. Chris D. says:

    <1 min. I hope… 🙂

  6. Andrew Mitchell says:

    Drew a picture. Hope the answer is right. Just took a minute.

  7. Chris Emerson says:

    Did you see the bit that said don’t post your answer?

  8. Oops…i thot i was mailing u…my bad…pl purge my response if possible…am new at this.

  9. Aseem says:

    P(n) = P(n − 1) + n

    • Waddett says:

      P(n) equation not the biggest answer…. possible to get more than that as pizza is a 3-dimensional object.

    • Juan AR says:

      @Waddett I think in this case we can assume that a pizza is a 2D object. If no, i choose the upper part.😉

    • Miggy says:

      How does this not count as posting your answer?

  10. Chris Emerson says:

    “As ever, please do NOT post your answers”

  11. Anonymous says:

    As ever, please do NOT post your answers…

  12. PreysQuall says:

    >.<

  13. PreysQuall says:

    1min 12sec the best LOL

  14. Sorry, but couldn’t be able even to read what is it about, this dish is so seductive indeed. lol

  15. Repton says:

    I exploit the curvature of the universe and cut the pizza into infinitely many slices with a single cut.

    • Michael Sternberg says:

      Ok you win!

      But even when sticking to Euclidian geometry the answer does depend an the dimensionality.

  16. We are not suppose to post the answer, if you like, it is instructed above. lol

  17. Berhard says:

    i have an euclidian solution but it seems quite unfair to some of the Pizza eaters. less than one minute…
    However i suppose it is not intended to place the whole pizza on a ape saddle shaped disch before cutting…

  18. Paul Durrant says:

    I think I have the answer, but I’m worried I might have overlooked some sneaky way of getting more.

    At least my way ends up with pieces of equal area, and equal amounts of base and topping in each piece, which might be important in a room of very hungry people!

  19. Andy Miles says:

    Now I am going to have buy pizza for lunch to test my answers…. bang goes the diet!

  20. AMWhy says:

    Got it in a second, but that’s because I’ve seen the same question before about a cake.

  21. Savant says:

    It’s not clear whether the pizza can be treated as a 3D object like a cake or just a 2D one. The answers are different; but then, a 2D pizza wouldn’t be very filling however big the slices were.

  22. Berhard says:

    The number of the solution also depends on the question if i habe to use always the same knive and if it might habe a curved / bend blade…

  23. Rayne says:

    I got 3 solutions in <1min. Now to see if any of them are right.

  24. mittfh says:

    Well, I have one solution that results in three different sizes of piece (multiple big, multiple small, and possibly one medium)… so I suppose if the party comprises both adults and children no-one will mind.

    Otherwise I’d suggest either cutting more slices or asking if anyone’s got the phone number to the nearest pizza delivery service to order additional ones…🙂

  25. Peter says:

    1 pizza for a room full of hungry people? Then cutting it into as many (i.e. small) pieces as possible? The answer can only involve personal injury!

  26. Lazy T says:

    If there isn’t a trick then it’s easy, if it does involve curved spacetime or multiverses then I’m stuck.
    and
    I’ve already had a bite out of it so that skews things too.

  27. Will says:

    Taking into account the considerable irregularity in the surface of the pizza…

  28. The other Matt says:

    Think i got it in 20 seconds. Had to check over a minute whether its the best solution.

  29. Blue Sky says:

    Maybe I can see the answer.

  30. Blue Sky says:

    I seriously think they should order more pizzas!

  31. Rich says:

    The original puzzle took place at a Pizza Hut in Croydon where everyone perished from hunger before it arrived. True story.

  32. infophile says:

    Hmm… We’re handed a knife, are we? Well, just take out a few extra knifes of your own, tape them to the sides of that knife, and cut away.

  33. infophile says:

    I’m pretty sure that doesn’t apply to joke answers… I certainly hope this isn’t the real answer, at least.

  34. Bletherskite says:

    About two seconds to get an obvious answer but then as it’s so obvious it’s bound to be wrong. Will ponder on ot some more

  35. Mad Kev says:

    If the straight line allows for the curvature of the Earth, then I’ve got it.

  36. Mad Kev says:

    Is it 7?

    • Anonymous says:

      you are right if pizza is flat. but if you consider its thickness, i can cut it higher than 7

  37. TS says:

    As long as I got the knife, I’m in charge.
    I’ll tie the pizza to a chair and dance around it singing “Stuck In The Middle With You”.

  38. Ray says:

    Got it! ( I hope)

  39. Ray says:

    Got it! (I hope)

  40. SimonP says:

    Can I hold the hungry mob at bay with the knife while I eat the pizza?

  41. lilovescake says:

    I have a solution (a few seconds) but it would be one heck of a lot easier if the pizza were a cake.

  42. dddave says:

    Two one answers, one if we assume the pizza is a 2D object, one for 3D. There’s a multiple set of answers based on if the pizza is deformed before we cut it.

  43. Mike says:

    I have an answer, but I doubt it’s correct.

    Just some thoughts, though:
    Even allowing for the curvature of the earth, if the line is straight it’ll finish where it started, and you can’t move the pizza because it’s too hot, so it’ll still be one cut.

    I think cheating by slicing the pizza in two thin pizza halves (effectively making a pizza sandwich) is wrong; some people wont get any topping, which is clearly unacceptable😉

    You could of course cut it into an almost infinite number pieces as you want using just three straight cuts, provided that they’re followed by as many curved cuts as you like :p

    (This is me cheating, and I hope it doesn’t constitute an answer)

  44. richard says:

    its trivial, in one sense. but can you make them all the same area (or volume for 3d cylinder pizzas)

  45. cabeza says:

    Pretty Hard..

  46. Dave Rickey says:

    There’s only one solution if we treat the pizza as a 2D object, another one if we can treat it as a 3D object (which seems to defy the “too hot to stack” instruction), and the solutions if we can deform it as a 2D object in 3D space (which seem even less reasonable) are probably limited but beyond my math/geometry skills.

    A few seconds to think of the 2D solution and straightforward 3D solution, a few minutes of musing to decide the more exotic geometric solution were too much work.

    –Dave

  47. […] It’s the Friday Puzzle! You face a room of very hungry people.  A large pizza arrives and you are handed a knife and asked to cut the pizza […] […]

  48. Engel says:

    Put Pizza down on record player and can get a whole lot of pieces with straight lines. Many angry guests who I assume will not fall for the is not vinyl, the pizza is just a bit burnt line however…

  49. Carl says:

    If my answer is correct, then it’s ridiculously simple. But I suspect there’ll be something much more impressive revealed.

  50. Jerry says:

    I think I see a solution, since the wording of the puzzle does not specify equal size pieces.

  51. pac0san says:

    Obtain an extra slice: transform an obviuos point into a triangle😉

  52. Marion says:

    Well I have two answers, want to say more about one but better not! Now to wait for the answer tomorrow.

  53. Mark says:

    Make as many cuts as you need, you’re the one holding a knife!

  54. Michael Carradus says:

    is it a thin pizza or deep pan?

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  56. Melvin says:

    wonderful app thanks for sharing

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