Happy Pi Day! Here's all you need to know

By Michelle Lou, Saeed Ahmed and Katia Hetter, CNN

If you've been using Pi Day as an excuse to just eat pie, that's just peachy (or apple or chocolate cream). But there's so much more to know about pi.

Here's why we care about pi and its day of celebration, which is March 14.

What is pi?

Pi is the ratio of the circumference of a circle to its diameter, or approximately 3.14.

What is Pi Day?

Pi Day occurs on March 14, because the date is written as 3/14 in the United States. If you're a serious math geek, celebrate the day exactly at 1:59 a.m. or p.m. so you can reach the first six numbers of pi, 3.14159.

March 14 is also Albert Einstein's birthday.

History of Pi Day?

Physicist Larry Shaw started Pi Day in 1988 at San Francisco's Exploratorium to celebrate the famous number and mathematics in general.

In 2009, the US House of Representatives passed a resolution to recognize Pi Day.

Who invented pi?

The mathematical concept of pi has been around for thousands of years, but it started to be known by the Greek letter only in the 1700s. Philologist William Jones began using the symbol in 1706, but it was popularized by mathematician Leonhard Euler.

Why is pi important?

Unless you're a mathematician or scientist, you probably don't encounter pi very often. But pi is essential for calculations in math, engineering, construction, physics and space exploration.

Does pi ever end?

Like our love for pie, pi is infinite. Its exact value can never be calculated, and it doesn't seem to have a pattern.

Here's pi to the 10,000th digit. You should recite it.

Who holds the record for reciting pi?

Rajveer Meena holds the record for reciting the most number of decimal places of pi. In 2015, Meena recited 70,000 decimal places blindfolded. It took him almost 10 hours.

For more information about pi, visit www.piday.org.