Pizza boxes are square for practical reasons

Detroit-style pizza's recipe nods to the Motor City

Legend has it that the rectangular pies were originally baked in blue steel pans intended to hold nuts and bolts in auto factories. The sauce poured across the top of the pies, meanwhile, is done so in straight lines called "tire tracks."

Taxicab geometry defines displacement as the sum of vertical and horizontal distances

In this mathematical system, pi is valued at four, and circles aren't round—they appear as diamonds with corners instead. The system simplifies pixel distances in digital imaging and helps engineers with robot navigation and chip design.

Are there any planets in the universe that aren’t round?

We think of all planets as spheres, but do they have to be spheres? To be classified as a planet, an object has to be sufficiently massive to reach a spherical shape through gravity. However, this doesn't mean they're perfectly round; for example, Earth has a slight equatorial bulge caused by centrifugal force from its rotation. Other observed planets feature tear-shaped formations while theorists posit donut-shaped planets. Read more here.

In 2001, Pizza Hut became the first company to deliver pizza to space

The chain paid the Russian space agency nearly $1M for the promotional stunt, which saw a Russian cosmonaut eat the pizza on video. Other unusual objects to make it to the International Space Station include a gorilla suit, an espresso machine, and several musical instruments.

Pyramid or plate? Why nutrition guidelines change

Those who remember growing up with the age-old food pyramid may be resistant to dietary guidelines changing, but experts agree that the food pyramid recommendations held serious flaws. It suggested, for instance, that meat and junk food were meant...

Cardboard thieves are making millions

The global market for recycled cardboard is worth billions of dollars—and it's attracting criminals. Specifically, people are making a fortune from taking used cardboard that's been left outside to be recycled, then proceeding to sell it. As a result, legitimate recycling firms and local authorities are missing out on millions. Learn more here.

It took 70 years for computer scientists to determine how to cut a cake fairly

The cake-cutting problem explores how to divide something fairly, which is not solely about cutting evenly-sized pieces. A protocol that accounted for personal preferences (e.g., a corner piece) between just three people took 16 years to develop.

Richard Cadbury invented the heart-shaped chocolate box in 1868

Richard's father, John Cadbury, founded the Cadbury Brothers chocolate company (now known simply as Cadbury) in 1824. Richard recognized the popularity of ornamental designs (especially for Valentine's Day gifts) and designed the heart-shaped box for the company's chocolates, which became a staple of the holiday.

All-you-can-eat buffets are a practical demonstration of economic ideas

Economists have noticed some restaurant goers prefer a flat pricing model despite it usually being more expensive than per-dish costs. The strategy behind endless servings includes concepts such as economy of scale, cross-subsidization, diminishing returns (of enjoyment of excess food), and more.

Was the stone that sealed Jesus's tomb round or square?

Archaeologist Amos Kloner's survey of more than 900 Second Temple-era burial caves found only four with round, disk-shaped stones—all belonging to the very wealthy. The other 98-plus percent used square, cork-shaped stones, suggesting the popular image of a wheel rolled away from Jesus's tomb is probably a later artistic invention. The Greek verb translated as "rolled" can also mean "moved."

Scientists now know why wombats poop cubes

For years, scientists have been wondering why wombat poop is cube-shaped (yes, really). Now, they say they have got to the bottom of the mystery.

Why roller coaster loops are never circular

The beloved looped roller coaster rides used to be shapes as perfect circles and constructed with wood, resulting in wobbly machinery that gave people whiplash. After the invention of steel and further scientific understanding, Six Flags debuted The Great American Revolution—a modern, oval loop with steel that offered a safer and smoother experience.

The perfectly rolled burrito depends on the tortilla

Experts recommend warming a tortilla before wrapping it around the filling. Once warm, you should distribute the ingredients evenly on the back half of the tortilla for a uniform shape.

Uncrustables' reinvention of the PB&J

In the 1990s, David Geske and Len Kretchman came up with the ingenious idea to package and mass-produce a crustless version of the peanut butter and jelly sandwich. This makeover to an American childhood staple resulted in a $1B business. Read this article in Mental Floss to learn more about the origins of the brand Uncrustables and its extraordinary success.

This flat map is still wrong, but it's the least wrong of all flat maps

While flat maps can never be as perfectly scaled as a globe, they're far more practical than carrying around a sphere. Researchers set out to minimize six major errors of flat maps, including boundary cuts and skewed proportions, by simply squashing...

Explore fun facts from the USPS, including unique post office buildings, a stamp that traveled past Pluto, and more.

Why cartoons only have four fingers

Ever notice cartoon characters only have four fingers? There’s a surprising reason why and it goes back to the first Mickey Mouse cartoons. From saving money to cultural taboos, here’s why animators draw hands this way.

Why are books released in hardcover and paperback?

Publishers regularly release books in hardcover only to rerelease them in paperback a year later. It's a strategy that might seem counterintuitive. Why spend so much time on two separate releases? And why spend so much money on two individual products? This Reader's Digest article goes behind the scenes in the publishing industry to answer these questions and others, offering insight into the intricacies of a complicated business.

How black boxes made flying safe

Black boxes—which are actually orange—were not universally present in airplanes until roughly 1967, a process which grew out of frustration over frequent, unexplained crashes in the industry's first few decades. This piece tells the origins of...

Sony set the standard for cylinder-shaped batteries when it repurposed manufacturing equipment used to make rolls of magnetic recording tape.

Why patterns in art are so pleasing

Repeated visual cues like shapes or lines derive from the brain's innate compulsion to identify faces, places, bodies, and more. With repeated shapes, the brain seeks out resolution to the subtle variations between them. See examples in art and music.

Bake bread like a Roman, and honor Ceres, the goddess of wheat

Grains made up about 70% of the Roman diet, and the word "cereal" stems from the goddess Ceres—the Roman equivalent of Greece's Demeter—to whom they prayed for good harvests. Cato the Elder, a famous statesman, left behind a simple home recipe for a Roman loaf.

Sony set the standard for cylinder-shaped batteries when it repurposed manufacturing equipment used to make rolls of magnetic recording tape.

Chess is played on an 8×8 board with 16 pieces per side

Chess begins with two players facing off on a checkered 64-square board. Each controls 16 pieces—king, queen, rooks, bishops, knights, and pawns—with the goal of checkmating the opposing king.

QR codes were developed in Japan in 1994 to fix bar code limitations

These codes store more data than traditional barcodes—up to 1,850 uppercase characters—and can be quickly scanned from any angle thanks to visual indicators like green squares and zebra-striped lines communicating orientation.

How does food move through the body?

Food passes through the digestive system via muscle movement known as peristalsis, during which a rippling contraction slowly pushes content through tubular organs, such as the esophagus and intestines. This is similar to what happens when one squeezes a tube of toothpaste, contracting the tube behind the content and forcing the tube in front of the content to expand, allowing the content to move forward.

Prairie style homes are low with dramatic horizontal lines

Prairie style houses are characterized by their long, low, and boxy open plans, emphasizing horizontal lines. Inspired by his upbringing in Wisconsin, Frank Lloyd Wright spearheaded the Prairie style and created houses according to this plan from 1899 to 1910.

Objects can be 3D printed with light by projecting 2D computerized tomography (CT) scans onto rotating cylinders of resin, which solidify upon exposure.

Up to a million Girl Scouts sell about 200 million cookie boxes every spring, generating $800 million, largely because refusing a child is frowned upon

Domino's Pizza's 30-minute delivery guarantee was responsible for the chain's 1980s surge, but it was discontinued after the company was found liable for delivery driver accidents.

SpongeBob exemplifies Aristotle's philosophy for living well because he understands that happiness doesn't come from external factors like money, recognition, or power.

Gerrymandering works through two techniques: cracking opposing voters across districts to dilute their power, and packing them into a few to waste their votes in lopsided majorities.

All rainbows are 'raincircles' caused by water droplets separating white sunlight into a spectrum of colors, but Earth's surface blocks the bottom half of the circle from our line of sight.

Larger animals like giraffes, elephants, and blue whales have developed a unique defense against cancer, a phenomenon known as Peto's Paradox

The history of many kitchen appliances involves unexpected discoveries and applications, including wartime radar turned hamster defroster and replacing an 'ice king' with heat-stealing boxes.

Fear or disgust related to clusters of holes and cracks, called trypophobia, may stem from evolutionary processes to help us avoid pathogens.

Power lines are dotted with large, brightly colored balls to improve the visibility of these thin wires to helicopters and small planes and help prevent potential crashes.

Exploring the Larry Bird punch that almost changed March Madness

Some coin denominations have ridges etched on their sides, partly to prevent counterfeiting, in a practice called 'reeding.'

Netflix profits when you're not watching, and its movies are designed that way—read a detail-rich critical essay exposing lesser-known Netflix takes

For centuries, it was common to sleep in two shifts: a few hours at the beginning of the night, and a longer period beginning around midnight

The hormonal disorder PCOS was renamed PMOS in 2026, a move designed to improve care and research by shifting the focus to the hormonal causes of this condition that affects 1 in 8 women.

'Silent' fireworks have gained more interest in recent years as a quieter celebratory option.

When you complete a CAPTCHA on a website to prove you are human, you may be unknowingly training algorithms for self-driving cars, whose systems require training data to help identify crosswalks, bicycles, and other outdoor objects.

Most of the observable universe's volume consists of voids and supervoids—enormous regions of space with little to no galaxies, stars, or light.

An initial public offering or 'IPO' is the process of a private company becoming public by putting shares of the company on the stock market for purchase.

Coral polyps reproduce via broadcast spawning, where entire reefs simultaneously release reproductive cells for about one hour, once a year.

Volcanoes 'die' when their supply of magma runs out, if they are shifted away from their underlying magma reservoir, or if they get clogged by collapsing or their magma cooling back into rock.

Budweiser stores yeast derived from the original 1800s strain in a secret bunker, which only the Head of Yeast Management can access—not even the CEO

Legendary architect Frank Lloyd Wright designed the SC Johnson headquarters in Wisconsin, aiming to make a cathedral-like workplace