e Day is an annual celebration of the mathematical constant e, of which the first six digits are 2.71828. The precise date on which it is celebrated is still the subject of some controversy, owing to variation in the final digit of e when evaluated to three significant figures, depending on whether a truncated or rounded approach is taken.
The first known celebration of e Day is believed to have occurred on January 27 1983, thus predating the very first Pi day by over five years. This happened when a group of second-year mathematics undergraduates at the University of Unter Über Schlesswig Holstein decided that they had had enough of calculus and were instead going to get blind drunk on several crates of low-quality, high-strength Weissbier. The resulting rampage through the town is estimated to have caused twenty-four million deutschmarks' worth of damage. However, the ringleaders avoided any punishment by pointing out the date, 27/1/83, and claiming that they were in fact celebrating the transcendental mathematical constant to five significant figures. Despite strong suspicions that this was a complete coincidence, the university and municipal authorities eventually backed down.
There were no further celebrations of e Day for several years after this, as mathematics departments in universities throughout the world maintained a state of high alert in case of any repetition of the Unter Über Schlesswig Holstein incident. However, when the first Pi Day went off without any apparent problems in 1988, a small celebration of e Day was allowed in 1990 and has continued thereafter.
As soon as the very first officially-sanctioned e day was announced, the potential celebrants immediately split into two camps. One - the Trunkees - maintained that in order to strictly preserve the digits of e, the number should be truncated to 2.71, meaning that the date of the celebration should take place on January 27. However, the Roundheads insisted that this was mathematically illiterate and that the number should be rounded up to 2.72, meaning that e Day should in fact occur on February 27. A number of Americans also tried to insist that neither of these was correct as the dates were in day/month order rather than the US standard month/day version, and there was a brief attempt to define what might be meant by either the 71st day of February or perhaps the 1st day of the 27th month. This was soon abandoned.
While this rivalry is often bitter it is usually non-violent, with any confrontation involving either a few hardcore Roundheads waving placards bearing the legend "Round Up the Trunkees!" at January 27 events or a similar number of Trunkees chanting "Two Four Six Eight! Euler says you must truncate!" at gatherings on February 27. Between the years 2016 and 2020 there was a brief fashion for Trunkee extremists to wear red baseball caps emblazoned with the slogan "Make e Truncate Again", but this MeTA faction appears to have largely disbanded for the time being.
From time to time, there are attempts by mathematicians of a more conciliatory nature to turn the celebrations into a two month event, with "Truncated e Day" occurring on January 27 and "Rounded e Day" on February 27. These people are usually derided as divergent centrists by both sides and the idea never gains any traction.
On October 12th 2007, the Committee to Understand, Resolve and Standardise E Day was formed in order to establish once and for all in which month e Day should be celebrated. However, it has been mired in arguments ever since and there is still no sign of a resolution in sight. It has been argued this has not been a complete waste of time, as several important academic papers have been generated on both sides of the debate and several PhDs have successfully been defended as a result.
Archie and Pye Day
The latest proposal has been put forward by a group of eminent Vavasorologists, who have proposed that e Day and Pi Day should be merged together as Archie and Pye Day, to take place on March 14 in order to (a) keep the Pi Day people happy and (b) to abandon any idea of consolidating e Day. This proposal has, however, been criticised as being nothing more than an attempt to publicise a bunch of indifferent novels by failed author Jonathan Pinnock.