Although National Pie Day is Jan. 23, it should not be confused with National Pi Day on March 14. The Greek letter "π" is also the letter that represents the value of the ratio of the circumference of a circle to its diameter.

The number pi, which begins 3.14, is irrational and therefore without an end. The University of Utah posted pi to 10,000 digits, and other websites have expanded the number even further.

Physicist Larry Shaw at the Exploratorium in San Francisco established Pi Day in 1988 and in 2009 the United States House of Representatives passed a resolution that officially recognized the day. National Pi Day has gained popularity over the years with more celebrations and events planned.

If you can't get enough of pi — or the pie that usually comes with it — get your nerd on with some of these celebration suggestions.

Related: Looking for the perfect Pi Day pie? Here are 25 recipes to help you out

The City Library Pi Day celebration

From 3-5 p.m., all Salt Lake City public libraries will host an event celebrating Pi Day with pies and spirographs.

Celebrate with Zaniac

The after school program Zaniac is hosting a Pi Day celebration at 1045 E. 2100 South in Salt Lake City. The first 20 K-8 students to register will participate in technology and math-based activities. Visit the Facebook event page for more information.

Grab a slice from the Pi

The Pie Pizzeria is holding a special for its Facebook friends, which will be announced Friday morning.

Get some exercise

If you prefer to celebrate pi with pie, you can also celebrate by working off that pie by walking, hiking or biking 3.14 miles.

For hikers, the Donut Falls trail in Big Cottonwood Canyon is roughly 3.14 miles long.

Using a stencil, iron-on or paint, create pi-inspired shirts, jewelry and other crafts using the pi symbol π.

Watch a 'pi' movie

Take a break and celebrate the day by enjoying a science-themed movie or a film that has something with "pi" in the title, such as "The Life of Pi" or an episode of "Magnum, P.I."

Take the Pi Day Challenge

Expand your thinking by trying out the Pi Day Challenge. The challenge is made up of a series of logic-based puzzles that will require you to use mathematical, research and other skills to complete.