“Pi Day” was celebrated in many countries on March 14. Pi (Greek letter “π”) is the name of a constant number in mathematics that represents the relationship between a circle’s diameter (its width) and its circumference (the distance around the circle). The value of the number is 3.1415926535… (and its digits go on forever). Over two trillion digits of pi after its decimal point have been calculated. Since March 14 is written as 3/14 in some countries, this day is celebrated as Pi Day. Many people ate and gifted food that was in the shape of a circle (pizza and pies) to celebrate the number. Albert Einstein, one of the world’s greatest scientists, was born on Pi Day. Here are some fun videos about pi.

### Did you know?

On December 31, 2009, Fabrice Bellard, a French computer programmer, set a new world record by calculating pi to 2.7 trillion digits.

### Did you know?

If a pizza has a radius “z” and height “a”, do you know what its volume is? The volume of a cylindrical shape is Pi*radius*radius*height, which is Pi*z*z*a.

*Image Credits: etc.usf.edu for Pi’s image*

*Sources: http://www.piday.org/, http://bellard.org/*