The U.S. government recognized March 14 as National Pi Day in 2009.
Ready to dig in?
Many pizza restaurants around the country will also be offering deals to celebrate Pi Day.
BJ's Restaurant Brewhouse is selling a mini one-topping pizza for $3.14 Thursday.
Download the 7-Eleven 7NOW app and you can order a pizza online for $3.14 with free delivery on Pi Day 2019.
A few other pizza places in Canada are offering $3.14 pizzas for Pi Day!
Not Jus' Donuts Bakery - Buy 1 slice of pie and get the second slice half off or buy a whole pie and get 15 percent off.
Cici's is offering an adult buffet for $3.14 with the purchase of another adult buffet and a large drink, with this coupon only.
San Diego Chicken Pie Shop: North Park's Chicken Pie Shop is celebrating Pi Day, offering their famous chicken pot pie, gravy, and a roll for $3.14, for dine-in or to-go orders.
It's also a day you can get sweet and savory deals on a pie with an "e". The grand prize victor will receive that perk and two other winners will get gift cards and merchandise.
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"Pie One, Get One" at Cheddar's Scratch Kitchen locations nationwide on March 14.
All Bakers Square customers can get $2 off whole pies on March 14. To that end, Schlotzsky's is celebrating by giving away a free bag of chips with the purchase of any entree.
Plated will offer free dessert for a year for first-time subscribers to its app.
Ooh La La - Receive half off a slice of pie of your choice. On Thursday, March 14, you'll get a free slice of Michigan ABC Crumb Pie (which includes apples, blueberries, and cherries) with any purchase at this Michigan-based pie shop.