You have a birthday cake and have exactly 3 cuts to cut it into 8 equal pieces. How do you do it?

 

Try figuring this one out on your own – as a hint we’ll tell you that you’ll have to “think out of the box” to get the answer. There is definitely something unique that you will have to do in order to come up with the answer. You can read the answer below.




The answer: stack the pieces

The “correct” answer is to cut the cake in quarters (4 pieces) using 2 of the cuts – one horizontally down the center of the cake and the other vertically down the center of the cake. This will leave you with 4 pieces (or slices) of cake. Then, you can take all 4 pieces and arrange them in a stack that is 4 pieces high. Finally, you can just cut that stack of 4 pieces in half – using your third and final cut – and then you will end up with 8 pieces of cake!

You might think of this as sort of a trick question, since moving the pieces is something “out of the box” – but somebody asking this question is probably looking for that kind of out of the box thinking.

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  • cynical

    This is exactly how i solved it!

  • SoE

    The question never stated the dimensions of the cake.

  • Guest

    can we cut it into half and then keep 1st half on 2nd half then then one horizontal cut and one vertical cut.

  • RS

    Cut 4 pieces at 45 degree angles – same as diving a wristwatch from 10:30-1:30 , 1:30-4:30, 4:30-7:30 and 7:30-10:30. Each piece is equal to 3 hours on a watch. Take the piece with 3 o’clock portion and align this with the 12 o’clock position. Similarly, align the 9 o’clock portion with 6 o’clock. Make sure all the center portions are aligned in one straight line which will pass through 3, 12, the cake cent6 and 9. A single cut along this line will give 8 exact pieces equal to 1:30 hrs on a clock. This does not require stacking which can destroy the cake icing etc. Enjoy the perfect 8 equal pieces.

  • mitch

    Those other solutions ( with the last cut horizontal) do not produce “equal” pieces. They wont all have frosting. 🙂

  • Rovin Varshney

    First make two cut, vertically and horizontally. Last cut will be parallel to the surface of the cake. This will leave the cake into 8 equal pieces.

  • jerraa

    If you cut it in 4 rectangular pieces, just cut through the side! You’ll get 8 pieces of half the width, half the height and half the dept. think of it lik you have 8 cubes and put them together.

    If you don’t get it, take 8 cubes (same size, just like in the puzzle) and put them together and try to make a bigger cube. If you do this you’ll get a cube with the size of 2 times the x, 2 times the y and 2 times the z.

  • Paul Alwin

    1st cut and 2nd cut perpendiculary and the last cut parelly to the surface

  • shamim

    If i divide from middle in the side of height. then horizontal and vertical.

  • Seeker

    First cut : Make a circular cut which shares the same center as the cake, with radius r1 = 1/sqrt(2)*r (where r is the radius of the cake), 2nd and 3rd cut are horizontal and vertical. the outer pieces and inner piece would have the same area. If strictly looking for same shaped pieces, this obviously won’t work !

  • Tim

    You could also just line them up rather than stack them because you can’t really stack cake!

  • tahmeed

    what about a a cross and then last cut will b horizontal?

  • varoon10

    Thanks Sai!

  • sairahul

    so tricky but easy answer thank you