It’s Pi Day! March 14th is the annual holiday dedicated to the ratio of a circle’s circumference to its diameter. Pi was first approximated thousands of years ago by the ancient Chinese, Babylonians, and Egyptians. Greek mathematician Archimedes gets credit for a more precise determination about 2000 years ago.

Since then, we’ve used technology to deepen our understanding and calculate Pi to greater lengths.

Recent computer programs use advanced formulas to calculate this irrational number well into the trillions of decimal places.

Pi Day was founded by physicist Larry Shaw in 1988. Activities and festivities get bigger and more creative every year. Many celebrate by making pies, of course. Other circular or Pi shaped foods are made, too. Others show their math appreciation through creative artwork, or throwing Pi themed office parties. Teachers even write special Pi Day lesson plans to emphasize the importance of the number.

**Fun fact:** If you’re feeling adventurous, see how many digits of Pi you can memorize. You’ll have to study hard to beat the record, though. It currently stands at 70,000 digits, and it took Rajveer Meena nearly 10 hours to recite them.

*Pi art made from circular pencil shavings. Source: https://commons.wikimedia.org/wiki/File:Pi-pjm.jpg*

In nature, we reference Pi when we talk about the bends and curves in the path of a river. It’s also found in calculations for theories related to electromagnetism, general relativity, and in the search for undiscovered planets. It’s safe to say that when you see circles, spheres, and elliptical shapes in nature, Pi is involved.

Because of this, its importance in science and engineering can’t be understated. It’s used daily to understand the geometry of almost anything related to circumference or arc length. Think engine pistons, orbital routes for NASA space probes, and the shape of an MRI machine. Each one requires a different level of accuracy, meaning the number of digits of Pi calculated depend on the tolerances required in the design.

**Fun fact:** NASA uses 16 digits of Pi, or 3.141592653589793, for interplanetary navigation calculations. Right now Voyager 1 is about 12.5 billion miles away from Earth. Calculating the circumference of a circle that size comes to about 78 billion miles. Stopping at the 15th digit of Pi means the numbers aren’t exact, but that’s still a margin of error of only 1.5 inches for a circumference of 78 billion miles!

** **We made Pi, of course! Our own small celebration in PTC Mathcad Prime 4.0 uses a few natural logarithms, traces, and coloring to create a stylized version of the Pi symbol (first used in 1706 by math teacher William Jones).

PTC Mathcad’s remarkable likeness to graph paper and its easy-to-use features give you tools to make engineering calculations neat and shareable, and fun! Want to download PTC Mathcad Prime 4.0 and practice for your next math holiday? Head over to the PTC Mathcad Prime 4.0 page and get started (CTA for PTC Mathcad 4.0?)