Pi is a mathematical constant. Pie is a delicious dessert. Given the diameter of a pie, pi could be used to find the circumference of the pie.

But it's probably best that you eat it instead.

Many around the world will do just that on Pi Day, which is celebrated on March 14 by obsessed mathematicians and pastry lovers alike.

The date, numerically 3/14, marks the first three of what turns out to be a string of infinite numbers, which never settle into any discernible pattern.

How irrational.

A World of Pi

Einstein lookalike contest

Celebrating Pi Day truly involves two avenues of thought. If you're keen on paying tribute to the intellectual side of things rather than eating tons of pie, that's your prerogative. And it's a call that won't go unanswered.

Interestingly enough, Pi Day is also Albert Einstein's birthday, so egghead activities abound.

Einstein lived in Princeton, N.J., for two decades, and his memory still inspires the locals to throw a major bash in his honor on Pi Day. This year, the town will hosts a 3.14-mile Pi Day Princeton bike ride — the procession moves in a circle, of course.

An Einstein exhibit features photographs as well as some of the scientist's personal belongings. Also, physicist Douglas Stone will talk about his book, Einstein and the Quantum: The Quest of the Valiant Swabian.

Pie eating contest

If all that sounds a bit weighty, consider the pie-eating contest, followed by an Albert Einstein lookalike contest. Consider also the event where people willingly submit to having pies thrown at them (that one helps raise money for local kids in need of financial assistance).

San Francisco's Exploratorium science museum also has a field day with Pi Day. The museum grants free access, and offers pi talks and exhibits. But the museum veers away from being overly stuffy, and also hosts a pizza pie dough tossing — outside, of course. Pie is served at the museum as well.

A World of Pi(e)

Pie is not limited to sweet things, as some pizza restaurateurs would readily remind you.

To that end, Your Pie, an Athens, Ga. -based fast-casual pizza franchise, offers on Pi Day tribute to the ratio that gives pizza its shape, with pies starting at $3.14. Thanks, math.

In Massachusetts, one bakery is making customers work for pie on Pi Day. Petsi Pies is asking guests to recite the digits of pi to receive a free sweet treat. Not millions of numerals, mind you. But it's still no walk in the park.

For a free personal pie, recite 10 digits of pi. For a free large pie, recite a whopping 314 digits. If you're a genius, you might be able to win a gift card good for one pie per season — but you have to recite 628 numbers.

If the thought of all reciting all of those numbers makes you dizzy, certainly don't visit this website, which continues to churn out Pi's numerals as the viewer scrolls down. But it's not infinite — the program eventually grinds to a halt after 1 million numbers.

It's enough to make one take solace in a sticky, warm fruit pie, an understandable reaction which can be fed with this recipe for Cherry Coke pie:

Cherry Coke Pie

The filling:

Cherry Coke pie

3 12-ounce bags of frozen dark, pitted, unsweetened cherries

1 can Cherry Coke

2-3 tablespoons cornstarch (two makes a looser pie, three makes a firmer filling)

Pinch salt

The crust:

Use your favorite recipe for a double crust.

We like this one for making the dough and this one to turn the dough into lattice.

Note the crust takes two hours to chill in the refrigerator.

You can also find pre-made crusts in the freezer section of your grocery store.

Make the filling:

Combine cherries and Cherry Coke in a medium-sized, heavy-bottom sauce pan. Add pinch of salt. Bring to a simmer, then turn heat down to simmer gently until cherry juice and soda are greatly reduced, about 45 minutes. Do not cook on high, or Coke sugars may burn.

Remove from heat. Ladle one spoonful of remaining juice into a small bowl and stir in cornstarch. Whisk with fork to make a slurry. Stir slurry back into cherry mixture and quickly bring back up to a simmer to activate the corn starch, stir then remove from heat. Put filling in a bowl and cool.

Make the pie:

Preheat the oven to 375.

Roll out two dough circles using instructions from the link above. Use one to fit in the bottom of the pie pan. Cut the other into 1/2- to 3/4-inch strips to make a lattice.

We used a fluted pastry cutting wheel to cut out our lattice strips. Lattice is optional; simply cut vent holes in the top crust if you want to skip that step.

Pour cooled filling into bottom crust. Cover top with lattice.

Crimp edges of crust as shown at the link above. Bake at 375 for 50 minutes, then cool on baking rack. Serve warm with vanilla ice cream.

Tip: Brushing the crust with egg wash gives it a golden-brown sheen.