Pi Day 2021

Celebrate Pi Day on March 14th, 2021 with Nine Planets.

Welcome to the officially unofficial Pi Day celebration! 🎉

On this page you'll find fun, geeky, information about pi, the magical math constant that is used (among other things) to measure the area and circumference of a circle.

And why, you might ask, is Pi Day celebrated on March 14th every year? Well, that's because if you round pi to two decimal places, you get 3.14. Which converted to a date, is the 14th of March.

Pi Day is a fun little holiday where we can celebrate pi, mathematics and its impact on the world, and eat pie! For example, we could use Pi Day as a way to remember the physicist Larry Shaw, who founded Pi Day way back in 1988.

What started as a mini-celebration with his co-workers at the Exploratorium science museum in San Francisco has now become a well-known holiday to celebrate this unique mathematical constant.


Countdown to Pi Day 2021

Are you as excited as we are about the next Pi Day on March 14th, 2021? Check out the countdown below to find out exactly how long we have to wait for some 3.14159 goodness.

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Pi is most commonly shown as being 3.14159 but this is just an approximate value. It's an irrational number, and its decimal representation never ends.

Take a look at what one million digits of pi looks like!

Interested to find out more about pi? Check out the links below.