e Day
I don't know what people do on e Day. So here is a picture of Euler skiing up the exponential function. The portrait of the function from Homeschool Math Blog e Day page.

March

14th Pi Day

Pi Day (also Albert Einstein's birthday)
On Pi day, people bake pi(es) and play with circles!

March Equinox
Celebrate by participating in the Noon Day Project, that commemorates and recreates what Eratosthenes did over 2200 years ago to determine very accurately the circumference of the Earth. This is a holiday celebrated four times of the year, on two equinoxes and two solstices.

Star Wars Day ("May the Forth...)
On this day, people practice Jedi Mind Math Tricks on one another. The traditional holiday attire is a pun t-shirt involving a formula.

June Solstice
Celebrate by participating in the Noon Day Project, that commemorates and recreates what Eratosthenes did over 2200 years ago to determine very accurately the circumference of the Earth. This is a holiday celebrated four times of the year, on two equinoxes and two solstices.

Software Freedom Day
On this day, people gift one another FOSS (free, open source software); create and share music, videos and other art made with free software; and get together to have local or online parties and seminars they can register at the day's site.

22nd-23rd The Equinox

September Equinox
Celebrate by participating in the Noon Day Project, that commemorates and recreates what Eratosthenes did over 2200 years ago to determine very accurately the circumference of the Earth. This is a holiday celebrated four times of the year, on two equinoxes and two solstices.

Celebrate 10/10 and especially 10/10/10 by watching the movies about powers of ten, listening to the Galaxy Song, and trying to visualize your place in the universe with interactives. Universcale works better than the infamous Total Perspective Vortex!

Also, Mary O'Keeffe points out that 101010=42 in binary.

On this day, participants host a show and tell of math art and puzzles, build math sculptures, and otherwise engage in advanced humanistic mathematics. They can also share math sculpture or math toy gifts.

Celebrate by participating in the Noon Day Project, that commemorates and recreates what Eratosthenes did over 2200 years ago to determine very accurately the circumference of the Earth. This is a holiday celebrated four times of the year, on two equinoxes and two solstices.

## Math Holidays

## Table of Contents

## January

## 15th Sonya Kovalevsky Day

Sonia Kovalevsky Day: Women Mathematician HolidayOn this day, girls and women get together and geek out mathematically - usually, solve fun problems and eat Pi.

Picture from University of Iowa Sonia Kovalevsky Day

## February

## 7th e Day

e DayI don't know what people do on e Day. So here is a picture of Euler skiing up the exponential function. The portrait of the function from Homeschool Math Blog e Day page.

## March

## 14th Pi Day

Pi Day (also Albert Einstein's birthday)On Pi day, people bake pi(es) and play with circles!

Pi pie, from Kitchen Daily

Google Pi Day logo, 2010

You can also celebrate by making a Pi necklace.

Or listening to how Pi sounds on piano.

More ideas from Math is not a crime blog.

## 20th-21st The Equinox

March EquinoxCelebrate by participating in the Noon Day Project, that commemorates and recreates what Eratosthenes did over 2200 years ago to determine very accurately the circumference of the Earth. This is a holiday celebrated four times of the year, on two equinoxes and two solstices.

Ihor Charischak's explanation of the holiday.

Erathosthenes page

## May

## 4th Star Wars Day

Star Wars Day ("May the Forth...)On this day, people practice Jedi Mind Math Tricks on one another. The traditional holiday attire is a pun t-shirt involving a formula.

T-shirt from Zazzle

Mind Tricks from Cut the Knot

## June

## 21st-22nd The Solstice

June SolsticeCelebrate by participating in the Noon Day Project, that commemorates and recreates what Eratosthenes did over 2200 years ago to determine very accurately the circumference of the Earth. This is a holiday celebrated four times of the year, on two equinoxes and two solstices.

Ihor Charischak's explanation of the holiday.

Erathosthenes page

## 28th Tau Day

Tau is double PiOn this day, people make music videos and art about Tau. They also discuss why it's way better than Pi!

## July

8th Math 2.0 DayMath 2.0 Community EventsOn this day, people play with math software and party in virtual math communities. It is the day Math 2.0 community was founded.

Hyperbolic Paraboloid party in Second Life

## September

## 18th Software Freedom Day

Software Freedom DayOn this day, people gift one another FOSS (free, open source software); create and share music, videos and other art made with free software; and get together to have local or online parties and seminars they can register at the day's site.

22nd-23rd The EquinoxSeptember EquinoxCelebrate by participating in the Noon Day Project, that commemorates and recreates what Eratosthenes did over 2200 years ago to determine very accurately the circumference of the Earth. This is a holiday celebrated four times of the year, on two equinoxes and two solstices.

Ihor Charischak's explanation of the holiday.

Erathosthenes page

25th Math Story DayMath Story DayOn this day, people tell stories and share digital stories. You can add links to your math stories and register your group.

Picture from ToonTalk "Resort Infinity" project

## October

10th Powers of Ten DayPowers of Ten DayCelebrate 10/10 and especially 10/10/10 by watching the movies about powers of ten, listening to the Galaxy Song, and trying to visualize your place in the universe with interactives. Universcale works better than the infamous Total Perspective Vortex!

Also, Mary O'Keeffe points out that 101010=42 in binary.

21st Gardner's Celebration of the MindGathering for Gardner: Celebration of the MindOn this day, participants host a show and tell of math art and puzzles, build math sculptures, and otherwise engage in advanced humanistic mathematics. They can also share math sculpture or math toy gifts.

OCT 31 = DEC 25Carol Cross's blog post about Natural Math people celebrating in 2010 by playing a Glass Bead Game

Mike South reminds us: Halloween is geek Christmas!

Hint: this joke refers to octal and decimal number bases. Here is the converter.

## December

## 20th-23rd The Solstice

December SolsticeIhor Charischak's explanation of the holiday.

Erathosthenes page

## Math ideas for mainstream holidays