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  • Who doesn't like birthday cake?

  • And, what I'm gonna show you today is that there are good ways and there are bad ways of cutting a cake.

  • And the classic way, the bad way, is like this, which will be normal.

  • You put the knife in the center, one bit of a slice, a bit of a slice.

  • That's not the classic.

  • It is the classic, isn't it? It's almost like a pie chart.

  • You know one thing about the word pie chart, in France,

  • they call them, Camembert, which is like a cheese.

  • It actually got a cheese chart in France.

  • Interesting cultural differences. enough speak

  • So, this is what you'll do, you take this, you'd put this over here.

  • You eat it, and you leave this in the fridge overnight.

  • And the reason why this is a really bad way of cutting a cake,

  • is that these bits here are just going to get dry.

  • And so when you come the following day to have your cake,

  • you do another one, another slice like this,

  • This side here, lovely and soft. This will be dry and horrible.

  • You know, maximizing the amount of gastronomic pleasure that you can make from this cake

  • there is a better way. A way that is more than a hundred years old,

  • and was discovered or invented by one of Britain's most famous and brilliant mathematical scientists.

  • This is a copy of Nature, the famous science magazine from December 20th, 1906.

  • In the letters to the editor here it says, headline, Cutting a Round Cake on Scientific Principles

  • The ordinary method of cutting out the wedge is very faulty

  • What he suggests is, and he gave a illustration for it,

  • tha proper way, the scientific way, the mathematically perfect way of cutting a round cake, and it is as follows.

  • So, we have another cake. The first slice will be like this.

  • It's breaking all the rules of a cake etiquette. Perfect. Okay. So, this is the first one.

  • And then I need to find a way of taking it out. We can set that there.

  • That's gotta be the prime steak of that cake, isn't it? It's the t-bone cut.

  • Here we need to do, we need to close the cake together like this, and it's gonna come apart.

  • So look what I got here, I have got some rubber bands to make sure it stays together.

  • The following day, all the flesh, the sponge is going to be nice and soft.

  • So, how do they do the second slice? The second slice, because it's not your birthday anymore,

  • so you're not gonna have this slice quite as big. Interesting to work out that actual proportion.

  • This is, and you got a lovely break into the elastic band too. it's exciting

  • This is slice two, or it actually is slice two which has two slices, two parts.

  • Good. So you put this back together. And we can keep on going,

  • Obviously again I want to use the elastic band to put the cake together.

  • That is perfect. That's gonna stay so fresh for day 3. Day 3, how should we do day 3 again?

  • Let's, um, turn it around. I think this is gonna be the slice for day 3.

  • Again, the satisfying snap of the elastic band.

  • I don't know if you thought of them before, but this triangular slices are really annoying anyway because it's not very satisfying.

  • Having a nice uniform slice like that is a lot better.

  • So, here we go again, it's the end of day 3.

  • And this is gonna be perfect, and gradually, we are slicing it. Keep on going.

  • I think for the, um, mathematical loners, who don't want to share their cake, it can be useful.

  • For a bit more interview including more about the guy who came up with this cake cutting method, have a look of the extra footage over on Numberphile2.

  • And if you just like to hear more great stories from Alex, he's got a new book out just recently,

  • Alex Through the Looking Glass, How Life Reflect Numbers and Numbers Reflect Life

  • It's really good, it's also just out in the US, but it has a different name in the US.

  • It's called, The Grapes of Math. I will put links to it in the video description.

Who doesn't like birthday cake?

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A2 UK cake slice cutting elastic pie chart chart

The Scientific Way to Cut a Cake

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    Tong-Ann Sytwu posted on 2014/07/02
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