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e-Day celebrates the mathematical constant e (2.7182818) on February 7 (2/7) in the month/day date format or January 27 (27/1) in the day/month format. See other special calendar dates!

Euler's constant "e" is commonly celebrated on February 7.
Euler's constant "e" is commonly celebrated on February 7.

What is e?

Euler’s constant “e” is also known as “Euler’s number” after the Swiss mathematician Leonhard Euler. The constant e was discovered by several mathematicians who didn’t know of its significance until Euler started to use the letter e for the constant around 1727. It is an irrational number that represents the idea that all continually growing systems are a scaled version of a common rate. The constant e is mostly used in logarithms, exponential growth, and complex numbers.

The letter e in e-Day is also used to represent other events and words that begin with the letter e.

What do people do?

Many celebrate e-Day as Euler’s constant day on February 7 (2/7) in the month/day date format. It is a day where people recognize the significance of the number e, which is approximately 2.71828. Although this is the most commonly recognized holiday for e-Day, there are other worldwide events that are observed that have nothing to do with the e number constant.

Euro day occurred in European countries that simultaneously adopted the Euro on January 1, 2002. In New Zealand, eDay is a day where people can get rid of e-waste or old electronics such as computers and old appliances, so they can be recycled rather than being placed in a landfill. Engineer’s Day is observed in Paducah, Kentucky on February 21 where many have an egg drop contest, create edible cars and tape people to walls. Eday is also an island in Northern Scotland.

e-Day Observances

WeekdayDateYearNameHoliday typeWhere it is observed
SatJan 271990e-DayWorldwide observance 
WedFeb 71990e-DayWorldwide observance 
SunJan 271991e-DayWorldwide observance 
ThuFeb 71991e-DayWorldwide observance 
MonJan 271992e-DayWorldwide observance 
FriFeb 71992e-DayWorldwide observance 
WedJan 271993e-DayWorldwide observance 
SunFeb 71993e-DayWorldwide observance 
ThuJan 271994e-DayWorldwide observance 
MonFeb 71994e-DayWorldwide observance 
FriJan 271995e-DayWorldwide observance 
TueFeb 71995e-DayWorldwide observance 
SatJan 271996e-DayWorldwide observance 
WedFeb 71996e-DayWorldwide observance 
MonJan 271997e-DayWorldwide observance 
FriFeb 71997e-DayWorldwide observance 
TueJan 271998e-DayWorldwide observance 
SatFeb 71998e-DayWorldwide observance 
WedJan 271999e-DayWorldwide observance 
SunFeb 71999e-DayWorldwide observance 
ThuJan 272000e-DayWorldwide observance 
MonFeb 72000e-DayWorldwide observance 
SatJan 272001e-DayWorldwide observance 
WedFeb 72001e-DayWorldwide observance 
SunJan 272002e-DayWorldwide observance 
ThuFeb 72002e-DayWorldwide observance 
MonJan 272003e-DayWorldwide observance 
FriFeb 72003e-DayWorldwide observance 
TueJan 272004e-DayWorldwide observance 
SatFeb 72004e-DayWorldwide observance 
ThuJan 272005e-DayWorldwide observance 
MonFeb 72005e-DayWorldwide observance 
FriJan 272006e-DayWorldwide observance 
TueFeb 72006e-DayWorldwide observance 
SatJan 272007e-DayWorldwide observance 
WedFeb 72007e-DayWorldwide observance 
SunJan 272008e-DayWorldwide observance 
ThuFeb 72008e-DayWorldwide observance 
TueJan 272009e-DayWorldwide observance 
SatFeb 72009e-DayWorldwide observance 
WedJan 272010e-DayWorldwide observance 
SunFeb 72010e-DayWorldwide observance 
ThuJan 272011e-DayWorldwide observance 
MonFeb 72011e-DayWorldwide observance 
FriJan 272012e-DayWorldwide observance 
TueFeb 72012e-DayWorldwide observance 
SunJan 272013e-DayWorldwide observance 
ThuFeb 72013e-DayWorldwide observance 
MonJan 272014e-DayWorldwide observance 
FriFeb 72014e-DayWorldwide observance 
TueJan 272015e-DayWorldwide observance 
SatFeb 72015e-DayWorldwide observance 
WedJan 272016e-DayWorldwide observance 
SunFeb 72016e-DayWorldwide observance 
FriJan 272017e-DayWorldwide observance 
TueFeb 72017e-DayWorldwide observance 
SatJan 272018e-DayWorldwide observance 
WedFeb 72018e-DayWorldwide observance 
SunJan 272019e-DayWorldwide observance 
ThuFeb 72019e-DayWorldwide observance 
MonJan 272020e-DayWorldwide observance 
FriFeb 72020e-DayWorldwide observance 

Quick Facts

e Day is held on either February 7 or January 27 to celebrate the mathematical constant e.

e-Day 2015

Tuesday, January 27, 2015
Saturday, February 7, 2015

e-Day 2016

Wednesday, January 27, 2016
Sunday, February 7, 2016


Name in other languages

Día del Número eSpanish
יום דואHebrew
يوم البريدArabic
전자 일Korean
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