From geeky calendar joke to played out internet trend to cheap pizza throw-down, Pi Day has evolved so much over the past 10 years. 

Celebrated annually on March 14 (3/14, like the mathematical constant – get it?), the day is perhaps best known around these parts for encouraging lots of restaurants to charge just $3.14 for an entire freaking pizza.

Lineups are inevitable, as this is Toronto.

Happy #PiDay, #Toronto! @pi_co_pizza is just one of the many places offering $3.14 pizzas today 🍕 #pizzaTO

A post shared by blogTO (@blogto) on Mar 14, 2018 at 10:02am PDT

Pi Co. is treating customers to personal, Neapolitan-style pizzas pizzas for the low, low price of $3.14 at all three of its locations between noon and 3:14 p.m.today.

#happy #nationalpiday - the #wait for a #personalpizza #314day @pi_co_pizza @blooryorkville #toronto #canada # #tofoodies #torontofoodie #torontofood #6 #416 #torontophoto #torontophotography #thesix #647 #the6ix #the6 #torontolife #torontoliving #torontolifestyle #yyz #tdot

A post shared by Kimberly Simmons (@canadiankas) on Mar 14, 2018 at 9:41am PDT

Blaze Pizza at Yonge and Dundas is similarly selling customized personal pies for $3.14, but their promotion lasts all day.

Customizable personal size pizzas for $3.14 at @BlazePizza today!🍕 #PiDay pic.twitter.com/VuVPWmHlL6

— The Eyeopener (@theeyeopener) March 14, 2018

Pizza Pizza is also doing free small cheese or pepperoni pizzas for $3.14 at all of its locations.

$3.14 PIZZAS HAVE BEGUN! Use online code: PIDAY to redeem. Tag your #PiDay pizza bud for a chance to win a $50 Gift Card!

Pi Day Restrictions: Online/mobile app only. Limit one coupon per order. Valid 11:00AM-3:14PM March 14th only. pic.twitter.com/b7n2CeFzhQ

— Pizza Pizza (@PizzaPizzaLtd) March 14, 2018

Those who aren't into pizza (what?) can get cheap actual pies at places like Pie Squared, The Rolling Pin and Kanga.

The rest of us will have marinara sauce stains around our mouths all afternoon.