Happy Pi Day: Do you know what that means?

Yes, it's Pi Day-- also known as March 14-- but a recent survey says some Americans have no idea what pi even is.

Pi (Greek letter "π") is the symbol used in mathematics to represent a constant -- the ratio of the circumference of a circle to its diameter -- which is approximately 3.14159. Remember 7th grade yet?

Pi has been calculated to over one trillion digits beyond its decimal point. As an irrational and transcendental number, it will continue infinitely without repetition or pattern. Pi was first calculated by Archimedes of Syracuse (287-212 BC), one of the greatest mathematicians of the ancient world. Every year, Pi Day is celebrated on March 14 around the world.

It's not only the day the world celebrates this very special number, but it also celebrates the birthday of scientist and mathematician Albert Einstein. National Pi Day has become a day to celebrate numbers and math-- and of course, to eat pizza pies and pie for dessert. Trust your inner geek on this one.

This year, researchers at NationalToday.com asked 1,000 Americans about everyone's favorite never-ending decimal number. Of those surveyed, one in five people said they have no idea what pi is. When asked what pi is a measure of, 66 percent of Americans guessed correctly--that it is a ratio of a circle's circumference to its diameter. Another 16 percent of Americans guessed incorrectly, while 19 percent admitted they have no idea what pi is.

Even if you can't remember all the way back to 7th grade, you can still celebrate with the best of them. The survey also found that 55 percent of people asked plan to celebrate Pi Day 2017-- most of them by eating pie. Others planned to post about it on social media, while 15 percent of those surveyed said they would walk or jog 3.14 miles in honor of the number. That's dedication (and a good way to burn off that pie).

Click here to learn more about National Pi Day.