**Celebrate Pi Day with us on this special #STEMCTEFridays post!**

Today, we honor a number that’s as special as it is tasty: pi!

Pi (π) is a mathematical constant that represents the ratio of a circle’s circumference to its diameter. Because π is often shortened as 3.14, many people celebrate this important number on March 14—or 3/14—by eating circular foods like pizza, donuts, and of course, pie.

In basic mathematics, Pi is used to find the area and circumference of a circle. You might not use it yourself every day, but Pi is used in most calculations for building and construction, quantum physics, communications, music theory, medical procedures, air travel, and space flight, to name a few.

**Pi Facts:**

**Pi is all-encompassing**– Mathematicians theorize that pi contains the numbers 0 through 9 in every conceivable combination, forming every possible string of digits. It is believed that your cell phone number, social security number, and every other string of numbers you can imagine are in pi. Then, if you convert letters into numbers, mathematicians theorize that every essay you’ve written and every book you’ve read is also believed to be present in pi.**Pi is ancient**– In the second millennium B.C., the Babylonians used 25/8 for pi (equivalent to 3.125), while the Egyptians are believed to have used 256/81 (equivalent to 3.160).**Computers have calculated pi to more than 22 trillion digits**– In 2016, a Swiss scientist, Peter Trueb, used a computer with 24 hard drives and a program called y-cruncher to calculate pi to more than 22 trillion digits — the current world record for the enumeration of pi. If you read one digit every second, it would take you just under 700,000 years to recite all those digits.**People have memorized vast stretches of pi**– The U.S. record is held by Mark Umile of suburban Philadelphia, who in 2007 recited more than 15,000 digits of pi.**Even rocket scientists only just over a dozen decimal places**– Though we know trillions of digits of pi, we don’t really need them. NASA engineers round pi off to 15 decimal places when calculating interplanetary trajectories.**Famous pi birthdays**– Albert Einstein and Stephen Hawking share a birthday with Pi Day!

**Pi Day Website:**

Celebrate pi on every day of the year on the **Pi Day website**!

**Learn more:**

**Pi Day Activities from NASA**to share with K-12 students and educators, parents, museums, science centers, and planetariums.- Fun activities related to pi and geometry from
**Little Bins for Little Hands**. - We love this list of
**18 ways that NASA uses pi**! - Kids will love this
**Pi(e) Making Challenge**from Galileo!

**More resources and activities:**

- Explore more resources and activities for
**Youth & Families**. - Have more STEM-learning fun with all of our
**#STEMCTEFridays**posts.