Every year on 14th March, we (or at least a very small number, probably only maths students) celebrate Pi Day. This is when the day and month match up to form the first 3 digits of the mathematical constant ‘Pi.’ Of course, this only works using the American (read ‘wrong’) method of dating whereby the month is put before the day.

14th March = 3/14 = 3.14

However, tomorrow, at exactly 9:26:53am and pm, we will experience a once in a lifetime event. An’exact’ Pi day. This means that not only will the day and month correspond with Pi, but the year, hour, minute, second, nanosecond etc will too!

14th March 2015 9:26:53 = 3/14/15 9:26:53 = 3.141592653

This event occurs every hundred years, on the 15th year of a century.

Many people have eagerly anticipated this event, with over 775,000 people saying they are ‘going’ to the Facebook event. There’s even a website selling hats, t-shirts and wristbands to commemorate the event.

The earliest official Pi Day was organised in 1988 by Larry Shaw at the Exploratorium museum in San Francisco.


Larry Shaw: copyright by Wikipedia user Ronhip

Some universities hold competitions on Pi Day, where the prize goes to the person who can recite the most digits of Pi. Other people just bake pies. I know which one I would rather do.


The world record for the most digits of Pi recorded using a computer is 10 trillion (10,000,000,000,000). But here are the first million for your enjoyment.

Happy Pi Day!