I am giving lots of talks over the next few days.  On Saturday I am at Think On in Cambridge and performing with the Festival of the Spoken Nerd.  On Sunday I am at the South Place Ethical Society in London and then on Tuesday I am speaking at the Anomalistic Research Unit in London.  Hope you can make it!

OK, to the puzzle.  Five people order a square pizza. The first person dives in an eats a quarter of the pizza. The other four people have to divide the remaining three-fourths into four equal and identically shaped slices. The cuts must be straight. How must they cut the remaining pizza in order to produce four identical slices?

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.

65 comments

  1. I’ve seen this one before, but not on this site.

    I know the answer, but I hope people are not going to complain about not having the same size of crust.

  2. I gave myself 10min to find a solution. Jotted down the frame with a pen, took my pencil and a rubber to start with a few trial and errors but a mere moment later I got it in the first try. Wow… must be my lucky day.

    1. Not quite… It says cut into 4 pieces, not 12 😉

      Not seen this one before but not a difficult puzzle to solve. I hope it’s a “take it to the edge” (or whatever they’re called) pizza, otherwise with my solution, some are going to complain about the distribution of crusts…

  3. As someone already said the first time you see this it can be quite a challenge but it’s quite well known.

    That said, there are some very good, less well known, and challenging variations on it. Wonder if Mr Wiseman (or someone else) can find any online.

  4. I love pizza, but it’s instant weight gain unfortunately. Thought this would be a hard one (oh Matron) but it only took a minute including a little simple maths.

  5. Sure I’ve seen it before, maybe on this site. I’m usually not great at these but I think I got this one and it only took a few seconds.

  6. if the straight cuts may be stopped in the middle of the pizza, then no problem…

    under a minute

    other solutions i did not find…

    1. Have you never been involved in a pizza-war?!!

      or course they have to be the same shape! and the greedy 1st person has to do extra chores to make up for their gluttony 😀

    2. Nick, why do they have to be the same shape?

      Why would the four complain if they each got the same amount, but not the same shape?

      Yours sincerely,

      uneducated in the ways of pizza etiquette.

  7. Good one …

    X X X X X X
    X X
    X X
    X X
    X _ _ X
    X ] X
    X ] X
    X X X X X X ] _ _ X
    X ] ] X
    X ] ] X
    X ] _ _ _ ] X
    X I X
    X I X
    X I X
    X X X X X X X X X X X

  8. Good one. If you take a stochastic, transformational approach and run this using Hergoves Regression it suddenly becomes clear ..

    X X X X X X
    X X
    X X
    X X
    X _ _ X
    X ] X
    X ] X
    X X X X X X ] _ _ X
    X ] ] X
    X ] ] X
    X ] _ _ _ ] X
    X I X
    X I X
    X I X
    X X X X X X X X X X X

  9. Took 4 attempts, quite easy once you realise it’s not as easy as you might think at first – if you see what I mean…

    1. The two diagonal cuts I think you have in mind lead to two different sizes, in which case it would seem the puzzle as it stands is already hard enough for you.

    2. attempting hard puzzles is good for the brain so i shall continue eddy despite your advice/

      the op (original puzzle) wants identical shapes not sizes. different sises are allowed by the op.

    3. But it says “…four *equal* and identically shaped slices…”

      That’s the whole point – that they each get the same amount.

      I would complain if two others got twice as much as me, which would be the case in your 2-diagonal scenario.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

w

Connecting to %s