Important Days in Mathematics

Pythagorean Theorem Day

Pythagorean Theorem Day is celebrated all over the world to celebrate the famous theorem of Geometry Pythagoras Theorem. The date of celebration is calculated using the Pythagoras formula. We know the Pythagoras formula states that the sum of squares of perpendicular and base is equal to the square of the hypotenuse. The date of celebration in a year falls on the day when the sum of squares of date and month equals the square of the last two digits of the year.


Pythagorean Theorem Day in year 2017 was 15 August, 2017. Let’s see how it is calculated.

Date = 15

Month = 8

Last two digits of year 2017 = 17

\(\therefore \) \(15^2 + 8^2 = 225 + 64 = 289\)

also, \(17^2 = 289\)

So, for 15 August, 2017, sum of squares of 15 and 8 is equal to square of 17.

This is how the date is calculated for Pythagorean Theorem Day.

The next Pythagorean Theorem Day in the future falls on 24 July, 2025.

Fibonacci Day

Fibonacci Day is celebrated on 23rd of November every year. It is celebrated to honour Italian mathematician Leonardo Bonacci, the most talented Western Mathematician of the Middle Ages. He is also known as Leonardo of Pisa and Leonardo Fibonacci. He introduced Europe to the Hindu-Arabic numeral system to ease the calculations with numbers unlike Roman numerals. He introduced one of the most influential sequence of numbers called as Fibonacci Numbers, which further derives a unique ratio in mathematics, called as “Golden Ratio”. Surprisingly, Golden ratio can describe many phenomenon of nature to financial markets.

Fibonacci day is celebrated on 23rd November every year and the date 11/23 is selected because the digits in 11/23 makes the part of Fibonacci sequence i.e. 1, 1, 2, 3.

Pi Day

Pi is the most famous number and a mathematical constant, which has a value of 3.142. It is observed on 14 March of every year. It is also known by the name of International Day of Mathematics from November, 2019 onwards. It is observed on 3/14 because the three digits 3, 1 and 4 makes the first 3 numbers of Pi value.

E-Day (Eulers Number)

E-day is celebrated to celebrate the mathematical constant e, which is called as Euler’s Number and has a value of 2.7182818. It is celebrated on 7th of February every year. The date is chosen from the the first two digits of the Euler’s Number.

Women in Mathematics Day

Women in Mathematics Day is celebrated worldwide on 12th of May every year. It is the day to celebrate for women in mathematics for their achievements in the field of mathematics and to encourage to an open, welcoming and inclusive environment for everybody. The events to celebrate the day take place from 1 May to 15 June.

List of important days in Mathematics

Name Date Website Link
Pythagorean Theorem Day Not a fixed date
Fibonacci Day 23rd of November every year
Pi Day 14th of March every year
Pi Day – Celebrate Mathematics on March 14th
E-Day (Eulers Number) 7th of February every year
Women in Mathematics Day 12th of May every year