## Lesson 3: Curiosities and Jokes (IV)

November 19, 2010

### The number Pi

The mathematical constant pi (π) is defined as the ratio of a circle’s circumference to its diameter. It is also the ratio between a circle’s area and its radius squared. It is approximately equal to 3.14159, but has been calculated to over one trillion digits.

### A Pythagoras’s student

The ancient Greek mathematician Pythagoras believed that all numbers were rational (could be written as a fraction), but one of his students Hippasus proved (using geometry, it is thought) that you could not represent the square root of 2 as a fraction, and so it was irrational.

However Pythagoras could not accept the existence of irrational numbers, because he believed that all numbers had perfect values. But he could not disprove Hippasus’ “irrational numbers” and so Hippasus was thrown overboard and drowned!

# Jokes

We will finish with

Popular Pi Jokes

• Q: What do you get when you take the sun and divide its circumference by its diameter?
• A: Pi in the sky.
• Mathematician: Pi r squared”
• Baker: No! Pies are round, cakes are square!

Click on The “Pi” Joke and you will watch a funny animation.

Here you are pi song

If you are in the mood you can listen the complete version here .

See you!!