Among the smallest mass-produced mechanical calculators in history, the Curta was designed by Austrian engineer Curt Herzstark while imprisoned in a Nazi concentration camp during World War II.

One of the first mechanical calculators—the Pascaline—was built in the 1640s by French mathematician Blaise Pascal to help his father, who worked as a tax collector.

Unsatisfied with the designs provided by an Apple engineer, Steve Jobs designed the original Mac calculator in about 10 minutes.

Designed in 1937 by Harvard graduate student Howard H. Aiken, the 'Harvard Calculator' was used by the US Navy to solve advanced physics problems.

The first commercially successful calculating machine—the arithmometer—was patented in 1820 but not mass-produced for over three decades, likely because its inventor was focused on his insurance business.

Slide rules—ruler-sized mechanical calculators with a component that slides out to show relationships between numbers—were used by engineers at NASA during the Apollo missions.

Nazi Germany replaced Advent calendars with depictions of family life under Nazi rule

During World War II, the Nazi regime banned printed Advent calendars because of religious messaging. Officials instead produced state-approved versions featuring swastikas, tanks, and Nazi symbols.

The Bauhaus artists who became Nazi collaborators

The Nazis deplored the Bauhaus style, until they found a way to use it for themselves. This deep dive explores the connection between the Nazis and three Bauhaus-affiliated designers—Franz Ehrlich, who was sent to Buchenwald and forced to design the camp's gates (seen below), Fritz Ertl, who designed the shower rooms at Auschwitz, and Herbert Bayer, who helped design Third Reich propaganda.

German printer Richard Sellmer revived Advent calendars after World War II

Advent calendar production resumed in 1946, when German printer Richard Sellmer began issuing nostalgic winter-town designs that became classics, later exporting them to the United States. His company still operates today, producing more than 140 varieties.

The history and operation of SIGABA, the US counterpart of the Nazi Enigma machine

Developed by the US Army and US Navy, over 10,000 of these machines were deployed by the end of World War II to encrypt messages for the armed forces using three series of rotors. The device would continue to be used until the 1950s, while personal computers were shown to possess enough computing power to crack it by 2021.

The Model K—named for its construction on a kitchen table—was the first electromechanical digital binary adder, which used an electric circuit to provide the sum of a pair of zeroes and ones in binary.

VisiCalc was the first electronic spreadsheet, released with Apple II's personal computer in 1979

Before 1979, managers were essentially information processors working off paper ledgers. Scenario modeling was slow, manual, and expensive. Companies were understood as organizations that built things with financial analysis as secondary. VisiCalc made calculation so cheap that you could work iteratively, setting out forecasts and tweaking assumptions until you got the answer you wanted. Oks argues It created a new way of seeing the world.

The treadmill was invented as a machine for prison labor

William Cubitt invented the machine in the early 1800s, imagining prisoners, usually two at a time, would use it to grind grain or pump water.

The first printed Advent calendars were from Germany in the early 1900s

Printed Advent calendars originated in early-20th-century Germany, where printer Gerhard Lang created the first commercially produced versions. Inspired by his mother’s homemade countdowns, Lang added small doors in the 1920s, establishing the format that spread worldwide.

The Antikythera mechanism: The oldest-known analog computer

A device now considered the world's oldest computer was pulled from a shipwreck more than 120 years ago. Known as the "Antikythera Mechanism," it is now believed to have allowed precise tracking of astronomical positions, and its sophistication overturned understanding of Ancient Greek capabilities.

Computer pioneer Alan Turing was also an elite runner

Alan Turing is credited with helping to found modern computer science, in addition to cracking the Nazi code known as Enigma. Beyond these world-historical achievements, the British mathematician also nearly represented his country in the Olympics in the marathon, running just 11 minutes slower than the eventual gold recipient at the 1948 games. Read more on this lesser-known aspect of the man here.

Grace Hopper was inspired to join the armed forces after the attack on Pearl Harbor

Despite being too old to enlist and weighing below the required minimum to serve, Hopper was granted an exemption and assigned to work on the first electromechanical computer produced in the US. She and her team spent three months using the device to solve equations needed to design the implosion mechanism for the atomic bomb.

The Bauhaus school developed a sleek typography that intentionally contrasted Nazi propaganda.

Clue, the murder-mystery board game, was designed during World War II air raids.

The QWERTY layout first appeared in the Sholes and Glidden typewriter, sold starting in 1874 by the E. Remington and Sons gun manufacturer, which was looking to diversify after the Civil War.

The first algorithmic random number generator was developed in 1946

Although previous methods of randomness involved physical tools with limited outcomes, such as dice, or relied on chaotic variables for number generation, such as electronic noise, John Von Neumann's middle-square method turned the problem into a mathematical computation. It has since been replaced by methods that generate numbers from unique initial values, such as the time on a clock.

A mysterious man named Emmerich Juettner once produced thousands of counterfeit $1 bills

After his wife died in 1937, Juettner fell into financial trouble and soon began replicating $1 bills. These bills aren’t typically prime targets for counterfeiting given their low value.

More than 2,000 years ago, a hand-powered model of the solar system called the Antikythera mechanism—the oldest example of an analog computer—could predict solar eclipses.

Abaci, the plural of abacus, allowed individuals to perform arithmetic and tally quantities by moving pebbles called calculi, from which the word 'calculator' is derived.

The foundation for computer viruses was published after its creator's death

In the late 1940s, Hungarian American mathematician, scientist, and engineer John von Neumann gave a series of lectures where he explained the theoretical framework for a computer program that could replicate itself—the von Neumann Universal Constructor. His lectures were later compiled and published in 1966, nine years after his death from cancer.

On a basic calculator, the keys that start with M, such as M+ and M-, are memory keys that allow users to store and modify a number in the device's memory.

Despite the abundance of free graphing software, Texas Instruments' de facto monopoly and the continued demand for its use in standardized testing have kept the cost and design of graphing calculators largely unchanged for decades.

At the age of seven, Grace Hopper dismantled alarm clocks

Foreshadowing a career in computers, Hopper exhibited a curiosity for gadgets at a young age and took apart seven clocks, determined to understand how they worked. Despite having a dollhouse, Hopper built an elevator for it and showed a greater interest in building toy furniture than playing with dolls.

Watch how the Enigma machine encrypts messages and learn about its critical design flaw

Using settings selected from a series of rotors and a plugboard that let operators swap letters with any of their choosing, the machine lit up the output letter for each letter typed. While this system could generate messages requiring any of 150 quintillion potential keys, the machine's reflector never encrypted a letter as itself, providing an entry point for exploiting the system.

View a library of custom programs that can be loaded onto graphing calculators, including productivity tools, reference materials, games, and interactive applications, such as prom proposals.

CES debuted in 1967 amid a wave of miniaturization in at-home electronics

The rapid development of integrated circuits—the basis of computing power—in the 1960s catalyzed an industrial shift toward miniature devices, including pocket transistor radios, smaller TVs, and more. This first consumer electronics trade show (with a slate of 117 exhibitors and 17,000 attendees) sought to make everyday electronics accessible and portable. See a timeline of early consumer tech with photos.

Against his wishes, Albert Einstein's brain was removed before his cremation, and the pathologist responsible stored it for decades in mason jars within a beer cooler.

Meet Clever Hans, the 1900s horse that was believed to be able to solve math equations and read German

When Clever Hans was prompted with math questions, he responded by tapping his hoof to indicate his answers. Even a panel of experts found no indication of trickery in the horse's demonstrations. However, psychology student Oskar Pfungst found that Hans stopped tapping once a subtle cue on his owner's face told him to stop. The cues were so subtle that Wilhelm von Osten didn't even know he was giving them.

US secrets: Project Paperclip

The US launched Project Paperclip in 1946, covertly recruiting over 1,500 German scientists to advance American military and space programs. Among them was Wernher von Braun, a key architect of the V-2 rocket who later became instrumental in NASA’s Apollo missions. While these scientists accelerated technological breakthroughs, their recruitment raised moral debates about overlooking wartime affiliations in the name of progress—questions that remain unresolved today.

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.

Try out an emulated version of the TI-84 Plus CE, the graphing calculator released by Texas Instruments in 2015.

A map of WWII refugees and their stories

Trace the paths of different people and families on this interactive map as they made their escape from the Nazi regime. Primary and secondary sources like letters, documents, memoirs and diaries, photos, interviews, and news clippings showed how many found a path to freedom, from the Kindertransport to individual stories.

In the 1980s, excerpts from fake diaries of Adolf Hitler were published in a prominent German magazine

Excerpts from the diaries were published in other publications around the world, like The Sunday Times, despite uncertainty about their authenticity. After forensic analysis, the diaries were proven to be fake. The diaries were produced by Konrad Kujau, a petty criminal who frequently produced counterfeits.

Explore Albert Einstein's Zürich notebook and review his notes on relativity

Within the pages are calculations, sketches and his first attempts at deriving what would be the field equations for gravity. It also documents some dead ends and the difficulties Einstein encountered as he describes part of the mathematics of what would become general relativity, describing it as "too involved."