# Blog

### World Cup squads and the Birthday Paradox

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England's squad for the 2018 World Cup is being announced today. 23 players will make the trip to Russia - and coincidentally 23 is also the number at which the chance of two people sharing a birthday reaches 50 per cent. In fact it's a shade over: 50.73 per cent. Yes, you read that right - with just 23 people gathered together, it's more likely than not that two of them will have the same birthday.
**Mark Mason**on 16-05-18 10:28. Comments (0)### The incredible ‘Birthday Problem'

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How many people do you have to gather together in a room before it becomes more likely than not that at least two of them will share a birthday? This teaser is something I mention on the Central Line walk (which passes the wonderful Gresham College, where I first learned about it.) For years I've struggled to convince people that the answer - just 23 - is correct. But recently I found a way of doing it that really brings the truth of the puzzle home ...
**Mark Mason**on 12-10-12 14:01. Comments (0)Showing **1** - **2** of **2** Articles

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### Other pages in this section...

### Books

### Walks

Inspired by my book *Walk the Lines: the London Underground - Overground*, each of these trivia-packed walks uncovers London’s history by following a section of a Tube line ... at street level.

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### Quizzes

Tailor made quizzes

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### Podcasts

Aural delights from the world of trivia

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