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.

Square Root Day

Square Root Day is the rarest mathematics day because it cannot be celebrated every year. Surprisingly, its occurrence is only 9 times in one century. It is celebrated on the days when both date and month are the square root values of the last two digits of the year. It was started by Ron Gordon, a high school teacher from Redwood City, California on September 9, 1981 (9/9/81).

The last square root day celebrated was on 4 April, 2016 (4/4/2016). The next upcoming Square Root Day is 5 May, 2025 (5/5/25). Let’s take an example of square root day and see how it is calculated.


February 2, 2004 (2/2/04)

day = 2, month = 2, year = 04

day = 2 = \(\sqrt{4}\)

month = 2 = \(\sqrt{4}\)

So, square root of year 04 is equal to both day 02 and month 02 of 2/2/04

List of Square Root Days in a century

DateDayMonthYearSquare root of year
January 1, 2001 (1/1/01)111\(\sqrt{1}\) = 1
February 2, 2004 (2/2/04)224\(\sqrt{4}\) = 2
March 3, 2009 (3/3/09)339\(\sqrt{9}\) = 3
April 4, 2016 (4/4/16)4416\(\sqrt{16}\) = 4
May 5, 2025 (5/5/25)5525\(\sqrt{25}\) = 5
June 6, 2036 (6/6/36)6636\(\sqrt{1}\) = 6
July 7, 2049 (7/7/49)7749\(\sqrt{49}\) = 7
August 8, 2064 (8/8/64)8864\(\sqrt{64}\) = 8
September 9, 2081 (9/9/81)9981\(\sqrt{81}\) = 9

Palindrome Day

Palindrome Day is the day of the year which makes same pattern like Palindrome. Palindrome is word or a number which can be read in both forward and backward directions and reading in both directions makes the same word or the number.

For a day to be a palindrome it must be in a format of mm/dd/yyyy or mm/dd/yy. The last palindrome day celebrated was 02/02/2022. The next upcoming palindrome will be 20/03/2023. Let’s find out below the next palindrome dates.


20 March, 2023

We can write it as 3/20/23 in m/dd/yy format.

The number sequence is 32023 in forward direction (left to right).

And, number sequence is 32023 in backward direction (right to left).

So, it is a palindrome because the number 32023 comes out to be same if read in either direction, which makes 3/20/23 as a palindrome day.

List of Palindrome Days

DateNumber in forward directionNumber in backward direction
March 20, 2023 (3/20/23)3202332023
March 21, 2023 (3/21/23)3212332123
March 22, 2023 (3/22/23)3222332223
March 23, 2023 (3/23/23)3232332323
March 24, 2023 (3/24/23)3242332423
March 25, 2023 (3/25/23)3252332523
March 26, 2023 (3/26/23)3262332623
March 27, 2023 (3/27/23)3272332723
March 28, 2023 (3/28/23)3282332823
March 29, 2023 (3/29/23)3292332923

List of important days in Mathematics

NameDateWebsite Link
Pythagorean Theorem DayNot a fixed date
Fibonacci Day23rd of November every year
Pi Day14th of March every year
E-Day (Eulers Number)7th of February every year
Women in Mathematics Day12th of May every year
Square Root DayOccurs 9 times only in one century