Pythagorean Theorem Day

We celebrate Pythagorean Theorem Day on December 16, 2020.

We all learned about the Pythagorean Theorem in high school Geometry. The theorem was created by a Greek Philosopher named Pythagoras. It is used to determine the longest side of a right triangle.

When is Pythagorean Theorem Day?

Pythagorean Theorem Day is celebrated on December 16 to recognize the importance of Pythagoras’ formula for right triangles.

Essentially, the theorem says that “For a right triangle with sides “A” and “B” and hypotenuse “C” that A squared + B squared = C squared.”

This holiday is celebrated differently timing-wise than other holidays. It is only celebrated on days that mimic the Pythagorean Theorem.

Let’s look closer at December 16, 2020. This date can be written as 12/16/20. If you square 12, you get 144. If you square 16, you get 256. And, if you square 20, you get 400. When you add 144 to 256, you get 400. Thus, the date qualifies!

2020 – December 16 = or 144 + 256 = 400

2025 – July 24 = or 49 + 576 = 625

2026 – October 24 = or 100 + 576 = 676

Pythagorean Theorem Day.

What is the Pythagorean Theorem?

The Pythagorean Theorem states the area of the square of the hypotenuse (the side of the triangle opposite the right 90-degree angle) is equal to the sum of the area of the squares of the other two sides.

Engineers, Architects, Surveyors, Designers, Construction Managers, and Electricians all use the Pythagorean Theorem. You may not have used it since high school geometry class, but other professionals have.

Who was Pythagoras?

Pythagoras was a Greek Philosopher and Mathematician born in 582 BC. He had many students and followers who adhered to his unique way of life and teachings.

It is unclear whether Pythagoras himself came up with the theorem that bears his name or if his students created the equation. Both Aristotle and Plato mention Pythagoras in their writings.

What Was the Pythagorean Secret Society?

Pythagoras was an interesting character, to say the least. While he was fascinated with numbers and mathematics, he was equally intrigued by music and the afterlife. In addition, he believed in transmigration, the idea that the human soul can move to another person or animal.

Pythagoras was so keen on transmigration that he instructed his followers not to eat meat. He also would not allow devotees to eat beans. He believed that passing gas lets some of a person’s soul into the atmosphere.

From the book Pythagoras His Life and Teachings by Thomas Stanley, here is some of the wisdom Pythagoras imparted to his followers:

Maintain silence for a long time.

You attain intense happiness when you have a good soul.

Excite your soul with music when you wake up, and soften the mind with music before you sleep.

Avoid the way of the crowds and pursue what is unique and holy.

Be just to all and expect equality.

Strive to make friends with virtuous people.

Your soul has two lives. One is within the body, and the other is outside it.

Practice receiving without resentment or envy.

There are many paths but choose the path that is best for you.

If you are patient and industrious, you must avoid lazy people.

Pythagorean Theorem Quotes

His sense of humor was permanently replaced by the Pythagorean Theorem.
Dima Zales

There is no answer to the Pythagorean Theorem. Well, there is an answer, but by the time you figure it out, I got 40 points, ten rebounds, and then we’re planning for the parade.
Shaquille O’Neal

Most people think that Pythagoras proved the Pythagorean Theorem, but in fact, it remained unproven until Euclid’s time, centuries later.
Rob Staeger

Science is the one culture that’s truly global – protons, proteins, and Pythagoras’s Theorem are the same from China to Peru. It should transcend all barriers of nationality; it should straddle all faiths, too.
Martin Rees

One cannot really argue with a mathematical theorem.
Steven Hawking

Pythagoras Quotes

Allow not sleep to close your eyes before three times, reflecting on your actions of the day. What deeds done well, what not, what left undone?

Educate the children. It won’t be necessary to punish the men.

Number is the ruler of forms and ideas and the cause of gods and demons.

Love that shines from within cannot be darkened by obstacles of the world of consequences.

Numbers are the highest degree of knowledge. It is knowledge itself.

The most momentous thing in human life is the art of winning the soul to good.

The oldest shortest words – yes and no are those who require the most thought.

There is geometry in the humming of the strings; there is music in the spacing of the spheres.

Friends are as companions on a journey who ought to aid each other to persevere on the road to a happier life.

Do not say a little in many words but a great deal in a few.

Pythagoras quotes and sayings.

Mathematical Days to Celebrate

Square Root Day – This day is celebrated like Pythagorean Theory Day. The date must match the Square Root. The next Square Root Day is May 5, 2025. The last one this century is September 9, 2081.

e-Day – This day celebrates the mathematical constant, which has a stated value of 2.7182818. Appropriately enough, it is celebrated each year on February 7 (2/7).

Pi Day – Again, the celebration of a mathematical constant, 3.1415926535, etc. The day is celebrated on March 14 (3/14).

Tau Day – Tau is quite controversial. There are mathematicians that want to replace pi was tau. Tau states that the ratio of a circle’s circumference to its radius is equal to 2 taus or 6.283. The day is celebrated on June 28 (6/28).

Fibonacci Day –This day celebrates a famous mathematician from the middle ages, Leonardo Bonacci. Bonacci is remembered for the Fibonacci sequence. An addition phenomenon where the two numbers that precede the third number add up to that number. For example, 1,1,2,3. 1 + 1 =2 1 + 2 = 3. The day is celebrated on November 23 (11/23).


To wrap up, here are a few Pythagorean Theorem jokes for you to tell at Holiday parties.

Zoologists know that Hippopotamuses can be especially dangerous. Because of this, they can’t get close to the hippos to measure the length of their backs. So, they use the Pythagorean Theorem to find the Hippotenuse.

The Bernoulli Principle, Newton’s Third Law of Motion, and the Pythagorean Theorem walk into a bar. The bartender looks up and says, “I’m not going to get this joke, am I?”

A Native American Chief has three wives living in three separate wigwams. One day he asks them if they would like new covers for their beds. The first wife replies that she would like a buffalo skin cover, the second asks for a bearskin cover, and the third asks for a hippopotamus hide for her bed. This proves the theorem “the squaw on the hippopotamus hide is equal to the other two squaws on animal skins.”

By Tim Moodie

Tim Moodie was not a good math student in high school. Nor was he a fan of geometry. However, he does enjoy a good triangle-shaped pizza slice now and then.


You’re on our National Pythagorean Theorem Day page.

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