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Math has spoken: You're cutting a cake all wrong

A fascinating exposition of humanity's laziness shows the mathematically efficient way of cutting your gateau.

Chris Matyszczyk
3 min read

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The first cut is the deepest, according to math. Numberphile/YouTube screenshot by Chris Matyszczyk/CNET

Ever since math began to control the world -- shortly after Larry Page and Sergey Brin started their little concern -- I gave myself over to the new power.

If math tells me that wearing red will make me more attractive, I do it. If math says it's better to find a new flame who looks just like my ex, I immediately want to pay $5,000 for the privilege.

And when math told me that my 38th girlfriend would make for the ideal wife, I naturally partook of the knowledge. Alright, she said no to my proposal, but that wasn't math's fault, was it?

Now, however, math is cracking its whip in my kitchen.

In a YouTube video that has taken on a peculiar virality, Alex Bellos and Numberphile have revealed that math is looking at your cake-cutting technique and sniggering like Julia Child after 10 snorts of gin.

We all seem to cut our cakes the same way. We take triangular slices. Why do we do this? Perhaps it's aesthetics. Perhaps we're just indolent and thoughtless.

The result of our slicing, however, is that the parts around the slices we've cut become dry and unpleasant to the mouth. Especially if we put the cake back in the fridge overnight.

"You're not maximizing the amount of gastronomic pleasure," says Bellow. And in today's world, just as in math, if you're not maximizing, you are a mini human.

In 1906, however, mathematician Francis Galton had already explained to cake-wasters to cut it out.

He insisted that if you slice the cake across the middle and take the first piece from there, you will not only have the most perfectly moist piece first, but also allow for the cake to be closed up again when it's put into the fridge.

This seems frightfully logical, as so much math does.

However, the next step tends to work against my own concept of maximizing gastronomic pleasure. Bellos shows that it's not so easy to put the two halves of the circular cake back together.

So he suggests placing a rubber band around the outside to assist you in your mathematically perfect quest.

I'm all for the rubber hitting the road, but when the rubber hits the cake, I find the idea mildly disturbing. Might the rubber affect the taste? I fear it might.

Worse, even when he puts the rubber band on, the cake resolutely refuses to look as new. It's as if it wants to snub its nose at math's quest for perfection.

Even worse, for the day two, post-fridge slice the knife should again cut in half -- but across a different diameter. This means it has to cut through the elastic bands.

Yes, it creates nice little flat pieces of cake. But then you have to get your hands dirty again, by squeezing the cake halves (now quarters) back together and reapplying an elastic band.

On day three, the elastic band, with the knife slicing through it, actually flies back toward Bellos. It's not happy.

You might adore eschewing the triangle by having a more uniform slice. You may marvel at how much fresh cake might be saved.

For me, though, this has to be a case of "Dear Math, it's not me, it's you. Sometimes, I just think you go too far."