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More or Less

The magical maths of pool testing

More or Less

BBC

News Commentary, Science, Mathematics, News

4.63.7K Ratings

🗓️ 19 September 2020

⏱️ 9 minutes

🧾️ Download transcript

Summary

Tim Harford speaks to Israeli researcher, Tomer Hertz, about how the mathematical magic of pool testing could help countries to ramp up their Covid-19 testing capacity.

Transcript

Click on a timestamp to play from that location

0:00.0

Hello and welcome to more or less on the BBC World Service,

0:03.5

with a programme that brings the stats out of Stasis and takes the numbness out of numbers,

0:08.1

and I'm Tim Halford. This week we're going to tell you what unites magic,

0:12.4

the Second World War, and Covid-19 testing. So let's start with the magic.

0:18.7

And I don't know if it's not that kind of magic. Mathematical magic.

0:22.3

That's better. With me is our Head of Department and actual magician, Hugh Levinson. Hello, Hugh.

0:33.2

Thanks so much. Thank you, Tim. It's great to be back on the programme. I'm going to try and

0:37.2

read your mind. And what I want you to do is I want you to think of a number. And quite a small

0:43.1

number, say up to about, I know, 60, 63. And I'd say maybe a number, it could be a birthday,

0:50.1

the date of a birthday or somebody special close to you, could be two digits from your pin number,

0:55.3

in which case I'll move them around and turn around. But think of something that's got a kind of

0:59.7

deep emotional meaning to you. My pin number, you reckon, has that? I'm sure it has a very deep

1:04.4

emotional resonance. And there'll already be letters because people will point out it's actually a pin,

1:08.9

not a pin number. A pin, you do sorry, your pin. That's pin. No, it's fine. Okay, now I'm thinking of

1:12.2

a number that is neither a birthday nor a pin, but that has an emotional resonance. That's super.

1:17.6

Now I've got six cards here with a whole load of numbers on them. Oh gosh. Okay, what I want you to do

1:22.0

is look through and see which of these has your number on. Right. It's like there's quite a lot of

1:27.6

numbers on them. There's like 20 or 30 numbers on each one. They seem to be pretty random. I'm

1:33.0

searching for my number. Okay, might it be on several of them? It might be. Okay, right.

1:40.0

Okay, I've gone through, I think it's on three of them and it's missing from three of them.

1:44.8

So the three you've got are the ones that you think it's on. Yes. Okay, so if you like to put those

1:48.4

down there between us and then reading deep into your soul, there's something that is deeply

...

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