National Pi Day is held each year on March 14. It honors 3.14 the ratio of the circumference of a circle. You can also get deals on food too.

We usually think of pi as about 3.14 – but there’s more to it than that. “Pi is a fabulous ratio that’s constant across every single circle,” Lesseig said.

What is pi? Pi can calculate the circumference of a circle by measuring the diameter — the distance straight across the circle’s middle — and multiplying that by the 3.14-plus number.

Pi is the ratio of a circle's circumference to its diameter. Jana Frank, a franchise owner of Mathnasium, shared some ways to celebrate Pi Day.

It's Pi Day! The ratio of a circle's circumference to its diameter is rounded to 3.14, making March 14 the day to celebrate.

What if we woke up one day and Pi wasn’t 3.14159 anymore? On March 14, the world celebrates Pi Day, honoring this essential number in mathematics. But what if the fundamental ratio of a circle’s ...

INDIANAPOLIS -- March 14 -- or, if you'd prefer, 3.14 -- is the informal holiday celebrating everyone's favorite irrational number, pi. The ratio of a circle's circumference to its diameter, pi is ...

National Pi Day is recognized on March 14 in the U.S. and around the world. Here's what to know about the quirky holiday, and how to celebrate.

As math lovers know, it's Pi Day. And what better way to celebrate than by rolling out the dough? An NPR editor known for her experimental baking shares some of her favorite recipes.

WHAT IS PI? Pi can calculate the circumference of a circle by measuring the diameter — the distance straight across the circle’s middle — and multiplying that by the 3.14-plus number.