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Dec16 Fun Holiday – Pythagorean Theorem Day

Pythagorean Theorem Day or Pythagoras Theorem Day is celebrated when the sum of the squares of the first two digits in a date equals the square of the last digit in the date.

The Pythagorean Theorem is one of the basic theorems in mathematics.

Every school child around the world learns the Pythagorean Theorem.

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The holiday gets its name from Pythagoras' Theorem, which defines the relationship between the sides of a right triangle or a right-angled triangle – a triangle where one angle is at 90 degrees. According to the Theorem, in a right triangle, the square of the hypotenuse (the longest side of the triangle) is equal to the sum of the square of the other two sides. The Theorem is named after Greek mathematician and philosopher, Pythagoras, who is thought to have formulated the proof for it.

The holiday is also sometimes called Right Triangle Day or Pythagoras Day.

Upcoming Pythagorean Theorem Days

Whether you write your dates in the mm/dd/yy format or the dd/mm/yy format, here are some dates you can celebrate this unique mathematical holiday in the near future.

  • August 15, 2017 (8/15/17 or 15/8/17): 8² + 15² = 17²
  • December 16, 2020 (12/16/20 or 16/12/20): 12² + 16² = 20²
  • July 24, 2025 (7/24/25 or 24/7/25): 7² + 24² = 25²

Other Mathematical Holidays

You don't have to wait for Pythagorean Theorem Day to celebrate mathematics. There are several other mathematical holidays throughout the year that honor mathematicians and their work. Some of these include Square Root Day, e-Day, Pi Day, Tau Day, Yellow Pig Day, Pi Approximation Day, and Fibonacci Day.

How to Celebrate?

Here are some ways you can make the most of this uncommon holiday:

  • Learn more about the Pythagoras Theorem and its real life applications.
  • Celebrate the day by eating foods that are cut in right angle triangles. Make a pizza or bake a cake or cookies in the shape of a right triangle. Too much work for you? Why not make triangular Rice Krispie treats?
  • Since the holiday depends on a unique date pattern, why not spend the day learning about other special date patterns. Use our Date Pattern Calculator to find out when's the next Sequential or Palindrome Day.

Did You Know...

...that dates and numbers that fulfill the relationship defined by the Pythagorean Theorem are called Pythagorean triples?

Pythagorean Theorem Day Observances

Fun Holiday: Pythagorean Theorem Day Observances
YearWeekdayDateName
2020WedDec 16Pythagorean Theorem Day
2025ThuJul 24Pythagorean Theorem Day

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