Did you know that for any 7 digit number, there's a 99.995% chance that it's found in the first 100 million digits of pi?

This mathematical curiosity has boiled over into Peek in Pi, an app for searching for numbers inside the digits of π.

Try it now: Peek in Pi

Searching for numbers in π works on the premise that you can treat the individual digits as essentially a random sequence. With than in mind, it's possible to calculate the chances of finding a set of digits of a given length:

These numbers were taken from this description of how the math works. Also from that page, this is the equation for how you calculate the number of digits:

The online app includes the first 10 million digits, which is a 10 MB download. It doesn't compress well because… the sequence is random! So the best we can do is ~4.5 MB compressed. Using 100 million digits would be… 10x larger! Which seems excessive for now.

No doubt we also need to add a premium version that includes the 100 million digits, or a 10s of billions of digits instead of the miserly 10 million we're offering now.

The app was first shown publicly at the Eyeo Festival back in 2012. Check out the 10 minute mark in this presentation.

Happy searching!

 

• Update 3/14/2026 – A few tweaks to fix the hideous CSS here, and placement of the About button on the search page.
• Update 6/3/2024 – Updated the search app to just 9 KB 8,785 bytes of vanilla JavaScript.
• Update 3/14/2017 – Posted a new online version searches the first 10 million digits from the comfort of your web browser (desktop or mobile). No installation necessary! Or for more digits, use the apps below. Happy π day!
• Update 4/12/2016 – Peek in Pi is now available for purchase as a watch face for Android Wear devices. Install it from the Google Play Store.
• Update 1/18/2016 – A version for Android phones and tablets is available from Google Play.
• Update 6/25/2014 – We celebrated Tau Day at Fathom, with a ¡FiesTau! blowout hosted by Jose.
• Update 6/19/2014 – The app was designed for mobile devices (phones, tablets), but we made a desktop version as well. It's available for Mac, Windows, and Linux.
• Update 3/24/2014 – After refusing a request for timely review so we could release in time for Pi Day, and rejecting the app as “not useful” a week later, Apple relented and posted it to the App Store.