Hidden in π

A foreword

Thank you, Hannah & Michael

This site exists because of one conversation. In an episode of The Rest Is Science, “Earth Is A Cradle But Not A Grave” (the π part starts at 38:00), Hannah Fry and Michael Stevens got talking about whether their own phone numbers are hidden somewhere in the digits of π. In the first 2 billion digits, they weren’t.

That sounded like a challenge. 2 billion digits feels like a lot, but a ten-digit number has less than a one-in-five chance (18%) of turning up that early: about 8.2 billion of the 10 billion possible numbers are still missing at that point. Search 100 billion digits instead and the odds flip: 99.995% of all ten-digit numbers are in there, and a typical one first appears around digit 7 billion.

So, Hannah and Michael: your numbers are almost certainly in here. We will never print them — but you are very welcome to come and look.

With particular thanks to Hannah, whose way of making mathematics feel like an adventure is the spirit this little site is trying to borrow.

— a fan

How the idea started

The question in the episode was simple: is my phone number in π? Looking it up by reading the digits one by one is hopeless, so this site does the reading once, in advance. It slid a ten-digit frame along the first 100 billion decimals and wrote down where every number first appears, so any search is one look in a table. How it works shows the whole trick in chalk.

Whether every number is in π is still an open question, and an honest answer deserved its own page: is every number really in π? Or skip the reading and find your own number.

Hidden in π is an unofficial fan project. It is not affiliated with or endorsed by The Rest Is Science, its hosts or its producers. Watch The Rest Is Science on YouTube.

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