What's Pi Day All About? Math, Science, Pies and More

A freshly sliced piece of chicken pot pie is plated on a counter at Michele's Pies, Wednesday, March 13, 2024, in Norwalk, Conn. (AP Photo/John Minchillo)
A freshly sliced piece of chicken pot pie is plated on a counter at Michele's Pies, Wednesday, March 13, 2024, in Norwalk, Conn. (AP Photo/John Minchillo)
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What's Pi Day All About? Math, Science, Pies and More

A freshly sliced piece of chicken pot pie is plated on a counter at Michele's Pies, Wednesday, March 13, 2024, in Norwalk, Conn. (AP Photo/John Minchillo)
A freshly sliced piece of chicken pot pie is plated on a counter at Michele's Pies, Wednesday, March 13, 2024, in Norwalk, Conn. (AP Photo/John Minchillo)

Math enthusiasts around the world, from college kids to rocket scientists, celebrate Pi Day on Thursday, which is March 14 or 3/14 — the first three digits of an infinite number with many practical uses.
Around the world many people will mark the day with a slice of pie — sweet, savory or even pizza.
Simply put, Pi is a mathematical constant that expresses the ratio of a circle's circumference to its diameter. It is part of many formulas used in physics, astronomy, engineering and other fields, dating back thousands of years to ancient Egypt, Babylon and China.
Pi Day itself dates to 1988, when physicist Larry Shaw began celebrations at the Exploratorium science museum in San Francisco. The holiday didn’t really gain national recognition though until two decades later. In 2009, US Congress designated every March 14 to be the big day — to hopefully spur more interest in math and science. Fittingly enough, the day is also Albert Einstein's birthday.
Here's a little more about the holiday's origin and how it's celebrated today.
WHAT IS PI? Pi can calculate the circumference of a circle by measuring the diameter — the distance straight across the circle's middle — and multiplying that by the 3.14-plus number.
It is considered a constant number and it is also infinite, meaning it is mathematically irrational. Long before computers, historic scientists such as Isaac Newton spent many hours calculating decimal places by hand. Today, using sophisticated computers, researchers have come up with trillions of digits for pi, but there is no end.
WHY IS IT CALLED PI? It wasn't given its name until 1706, when Welsh mathematician William Jones began using the Greek symbol for the number.
Why that letter? It's the first Greek letter in the words “periphery” and “perimeter,” and pi is the ratio of a circle's periphery — or circumference — to its diameter.
WHAT ARE SOME PRACTICAL USES? The number is key to accurately pointing an antenna toward a satellite. It helps figure out everything from the size of a massive cylinder needed in refinery equipment to the size of paper rolls used in printers.
Pi is also useful in determining the necessary scale of a tank that serves heating and air conditioning systems in buildings of various sizes.
NASA uses pi on a daily basis. It's key to calculating orbits, the positions of planets and other celestial bodies, elements of rocket propulsion, spacecraft communication and even the correct deployment of parachutes when a vehicle splashes down on Earth or lands on Mars.
Using just nine digits of pi, scientists say it can calculate the Earth's circumference so accurately it only errs by about a quarter of an inch (0.6 centimeters) for every 25,000 miles (about 40,000 kilometers).
IT'S NOT JUST MATH, THOUGH Every year the San Francisco museum that coined the holiday organizes events, including a parade around a circular plaque, called the Pi Shrine, 3.14 times — and then, of course, festivities with lots of pie.
Around the country, many events now take place on college campuses. For example, Nova Southeastern University in Florida will hold a series of activities, including a game called “Mental Math Bingo” and event with free pizza (pies) — and for dessert, the requisite pie.
“Every year Pi Day provides us with a way to celebrate math, have some fun and recognize how important math is in all our lives,” said Jason Gershman, chair of NSU's math department.
At Michele's Pies in Norwalk, Connecticut, manager Stephen Jarrett said it's one of their biggest days of the year.
"We have hundreds of pies going out for orders (Thursday) to companies, schools and just individuals," Jarrett said in an interview. “Pi Day is such a fun, silly holiday because it’s a mathematical number that people love to turn into something fun and something delicious. So people celebrate Pi Day with sweet pies, savory pies, and it’s just an excuse for a little treat.”
NASA has its annual “Pi Day Challenge” online, offering people plenty of games and puzzles, some of them directly from the space agency's own playbook such as calculating the orbit of an asteroid or the distance a moon rover would need to travel each day to survey a certain lunar area.
WHAT ABOUT EINSTEIN? Possibly the world's best-known scientist, Einstein was born on March 14, 1879, in Germany. The infinite number of Pi was used in many of his breakthrough theories and now Pi Day gives the world another reason to celebrate his achievements.
In a bit of math symmetry, famed physicist Stephen Hawking died on March 14, 2018, at age 76. Still, Pi is not a perfect number. He once had this to say:
“One of the basic rules of the universe is that nothing is perfect. Perfection simply doesn’t exist. Without imperfection, neither you nor I would exist.”



Cactus Pear Is a Crop with Potential in Italy’s Parched South and Beyond

Prickly pear cactus plantation is seen in Tepeteopan, state of Puebla, Mexico January 16, 2020. Picture taken January 16, 2020. (Reuters)
Prickly pear cactus plantation is seen in Tepeteopan, state of Puebla, Mexico January 16, 2020. Picture taken January 16, 2020. (Reuters)
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Cactus Pear Is a Crop with Potential in Italy’s Parched South and Beyond

Prickly pear cactus plantation is seen in Tepeteopan, state of Puebla, Mexico January 16, 2020. Picture taken January 16, 2020. (Reuters)
Prickly pear cactus plantation is seen in Tepeteopan, state of Puebla, Mexico January 16, 2020. Picture taken January 16, 2020. (Reuters)

Global warming, drought and plant disease pose a growing threat to agriculture in Italy's arid south, but a startup founded by a former telecoms manager believes it has found a solution: Opuntia Ficus, better known as the cactus pear.

Andrea Ortenzi saw the plant's potential 20 years ago when working for Telecom Italia in Brazil, where it is widely used as animal feed. On returning to Italy he began looking at ways to turn his intuition into a business opportunity.

He and four friends founded their company, called Wakonda, in 2021, and began buying land to plant the crop in the southern Puglia region where the traditionally dominant olive trees had been ravaged by an insect-borne disease called Xylella.

The damage from the plant disease has been compounded by recurring droughts and extreme weather in the last few years all over Italy's southern mainland and islands, hitting crops from grapes to citrus fruits.

Ortenzi is convinced the hardy and versatile cactus pear, otherwise called the prickly pear or, in Italy, the Indian fig, can be a highly profitable solution yielding a raft of products such as soft drinks, flour, animal feed and biofuel.

The Italian businessman is far from alone in seeing the potential of the plant, whose cultivation is expanding in hot and dry regions around the world.

"As an industry, cactus pear production is growing rather quickly, especially for fodder use and as a source of biofuel," said Makiko Taguchi, agricultural officer at the United Nations' Food and Agriculture Organization headquartered in Rome.

MULTIPLE USES

The cactus produces a tasty fruit eaten in much of Latin America and the Mediterranean, while in Mexico the flat green pads that form the arms of the cactus, are used in cooking.

In Tunisia, where it covers around 12% of cultivated land, second only to olive trees, the cactus pear is a major source of income for thousands, particularly women who harvest and sell the fruit.

In Brazil, which has the world's largest production, it is mainly cultivated in the north-east for fodder, while Peru and Chile use it to extract a red dye known as Cochineal, used in food and cosmetic production.

Sportswear group Adidas and carmaker Toyota have recently shown interest in using the cactus to produce plant-based leather sourced mainly from Mexico.

The cactus pear is not yet included in the FAO's agricultural output statistics, but Taguchi cited the rapid expansion of CactusNet, a contact network of cactus researchers and businesses worldwide which she coordinates.

The FAO launched the group online in 2015 with 69 members. It now has 933 members in 82 countries. The plant, native to desert areas of south and north America, thrives in the increasingly arid conditions of Italy's south, and needs ten times less water than maize, a comparable crop whose byproducts also include animal feed and methane.

So far Wakonda, an American Indian word meaning nature's omnipresent creative force, has planted just 10 hectares of cactus with 40,000 plants per hectare, but Ortenzi plans to plant 300 hectares by the end of 2025, and he is thinking big.

Of the roughly 100,000 hectares of olive trees destroyed by Xylella in southern Puglia, only 30,000 will be replanted in the same way, he told Reuters in an interview.

"Potentially 70,000 could be planted with prickly pears," he said.

In the long run the possibilities could be even greater, Ortenzi said, considering more than a million hectares of arable land have been abandoned in Italy in recent decades as climate change has made it more difficult to produce traditional crops.

WAKONDA'S MODEL

Wakonda's business model discards the fruit and focuses instead on the prickly pads, which are pressed to yield a juice used for a highly nutritious, low-calorie energy drink. The dried out pads are then processed to produce a light flour for the food industry or a high-protein animal feed.

Wakonda's circular, ecological production system also includes "biodigester" tanks in which the waste from the output cycle is transformed into methane gas used as a bio-fuel either on site or sold.

The company, which now has 37 shareholders, is in contact with mayors, firms and universities to develop its products.

Under Ortenzi's business plan, rather than buying up land to plant the cactus, Wakonda aims to persuade farmers of its potential and then license out to them, in return for royalties, all the equipment and know-how required to exploit it.

"The land remains yours, you convert it to prickly pears and I guarantee to buy all your output for at least 15 years," Ortenzi said.