What Is Pi Day?
Pi Day is on March 14. In the US, the date is 3/14. This looks like 3.14. And 3.14 is a very important number in math. It is called "pi."
What Is Pi?
Pi is a number. Pi is the circumference of a circle divided by its diameter. The circumference is the distance around a circle. The diameter is a line across the center of a circle. Pi is about 3.14159. Actually, the number continues forever!
The radius is half of the diameter. You can use pi to find the area of a circle, too.
How Did Pi Day Start?
In 1988, a man named Larry Shaw started Pi Day. He worked at the Exploratorium in San Francisco. People there wanted to celebrate math and science. In 2009, the US government said, "Yes, Pi Day is important!" March 14 is also Albert Einstein's birthday. So it is a big day for math and science.
Math and Pie Go Together
Pi Day is fun because it is not only about math. "Pi" and "pie" sound the same! So on Pi Day, many people eat sweet pie. Some people eat pizza pie, too. Math and pie go together on Pi Day. It is a day for numbers and a day for food.
Pi in Space
Pi is not just for events at school. NASA uses pi every day. NASA uses pi to find the area of a parachute. NASA uses pi to imagine the size of a planet. NASA uses pi for round fuel tanks, too.
Here is something interesting. Imagine a very big circle in space. The radius is 46 billion light-years. To find the circumference of this circle, you need pi. But you need only 37 numbers after the point. That is enough!
Try It on Pi Day
On March 14, you can celebrate Pi Day. You can talk about the number pi. You can learn about circles, the diameter, the radius, and the area. And you can eat a sweet pie! Pi Day is a fun culture event for math, science, and food.










