Thank you for downloading the more or less podcast. We are Weekly Guide to the Numbers in the News and in Life, and I'm Tim Harford.

This week we're going to be grappling with some mind-bogglingly enormous numbers,

way beyond the millions, billions and trillions, even beyond the quadrillians, quintillions or

sextillions, to figures that are incredibly hard for the human mind to comprehend.

Listener Prashant Rao wrote to the program after an interesting claim he'd come across in a novel.

Literary criticism is normally our source for figures, but all

number-based queries are welcome here and more or less. In the book, The Midnight Library

by Matt Haig, a character says there are more possible ways to play a game of chess than the amount of atoms in the observable universe.

The internet is littered with articles and blogs that repeat this claim, so we thought

we'd examine it. First step, let's look at chess. What can we say about the number of possible ways to play a game?

We asked mathematician Dr James Grimes, a content curator at the Discovery Center, Maths City.

So the estimate that we've got is... Discovery Center, Maths City.

So the estimate that we've got is a very big number, which is 10 to the power 120.

So it does imagine a piece of paper with a 1 and 120 zeros after it. It's a absolutely huge number.

It's called the Shannon number, which is named after Claude Shannon.

Claude Shannon was a pioneer of computer science, someone who should be mentioned in the same breath as Alan Turing.

And Claude Shannon was considering how he could program a computer to play chess.

What would that involve, how difficult a problem that would be?

So you could program your computer to consider the next move and all the possible next moves it could do and it could pick the best one.

Or even going to an extreme, it could start from the beginning and just have a look at every possible game and

then pick the best move to start with but that involves thinking about every

possible chess game and that's where Shannon started to estimate how many possible chess games that are.

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