Pi day

Pi Pie (a π cake with π rounded to 27 decimal places), made at the Technical University of Delft

Larry Shaw, the "founder" of Pi Day, at the Exploratorium in San Francisco

The Pi day ( English Pi Day ) is a day celebrated by its followers in honor of the circle number Pi. It takes place on March 14 of each year and is based on the US date notation 3/14 (or ISO notation -03-14), which contains the first three digits of π: 3 , 14.

Larry Shaw , who initiated Pi Day in 1988 at the Exploratorium in San Francisco , where it has been celebrated annually since then, is considered the founder of this tradition . In 2009, March 14th was declared the official national day for the circular constant Pi by the US Congress.

The Pi Day is traditionally celebrated with the common eating of circular cake (in English the Greek letter π is according to the same as the English word pie , cake pronounced). Such a cake with a diameter of 20 centimeters also has a footprint of π square decimeters.

The fact that 14 March happens to be Albert Einstein's birthday and (since 2018) the anniversary of Stephen Hawking's death also helps to spread the day of remembrance . Particularly accurate followers celebrate at 13:59:26 and thus reach the circle number up to the seventh decimal place (3/14 1:59:26 pm). At MIT in 2015, some appointments were set for Saturday, March 14th at exactly 9:26 a.m. ET thinking about Pi (3/14/15 9:26 am).

On the other hand, a Pi Approximation Day will be celebrated on July 22nd , with which the approximate representation of π by Archimedes as 22/7 ≈ 3.14 is to be honored.