The history
4,000 years from pebbles on a board to a solar-powered chip in every school bag.
For thousands of years people added by moving pebbles and beads between columns, and India gave the world the digits 0 to 9 with zero. Inventors then built gears that carried tens by themselves, and offices filled with cranked and key-driven machines. In the twentieth century switches, tubes and transistors took over, and in 1971 a calculator's brain became the first microprocessor. Today a calculator runs on a scrap of light.
1851
First commercially successful mechanical calculator
Thomas de Colmar's arithmometer, France
1961
First all-electronic desktop calculator
ANITA Mk VII and Mk VIII, Bell Punch, UK
1967
First handheld electronic calculator prototype
Cal Tech, Texas Instruments, USA
1971
First commercial microprocessor, made for a calculator
Intel 4004 for the Busicom 141-PF
1972
First handheld scientific calculator
HP-35, Hewlett-Packard, USA
1973
First LCD calculator
Sharp EL-805, Japan
1978
Among the first to run on light alone
Teal Photon
1985
First graphing calculator
Casio fx-7000G, Japan
2700 BCE – 1600
Pebbles on ruled boards, the Chinese bead abacus, and India's place-value digits with zero.
2500 BCE
c. 2700–2300 BCE
Some historians think the Sumerians of Mesopotamia were the first to reckon on a counting board, moving pebbles between ruled columns. No board survives, so the date is uncertain.
Why it mattered. Moving tokens between columns is the first place-value machine: each column worth more than the one beside it.
300 BCE
c. 300 BCE
A marble counting board about 1.5 m long, found on the island of Salamis in 1846, is the oldest counting board known to survive. Pebbles on its ruled lines stood for units, tens, hundreds and more.
Why it mattered. It shows that adding by moving counters between columns was everyday work more than 2,000 years ago.
190
c. 190 CE
A book credited to Xu Yue is thought to be the earliest written description of the suanpan, the Chinese bead abacus, though scholars debate exactly what it describes. By the Ming dynasty the suanpan, with 2 beads above the bar and 5 below, was used across China, and trained users could add faster than early mechanical calculators.
Why it mattered. A bead frame keeps a number as positions in columns and adds by carrying from one column to the next, just like the adder in this box.
628
628 CE
In his Brāhmasphuṭasiddhānta, Brahmagupta gave rules for adding, subtracting and multiplying with zero and negative numbers. Indian mathematicians worked sums on dust boards (pāṭī) using the place-value digits 0 to 9, and India also knew counting boards, though how widely they were used is debated.
Why it mattered. The decimal place-value system with zero, which travelled from India to the world, is what every calculator displays.
1600 – 1950
Napier's rods, Pascal's and Leibniz's machines, the arithmometer and the key-driven Comptometer bring calculating into offices.
1617
Napier, the inventor of logarithms, published a set of numbered rods in his book Rabdologiae. Laid side by side, the rods turn multiplication into reading off and adding small numbers along diagonals.
Why it mattered. It broke multiplication into simple additions, the same idea as shift-and-add in a calculator chip.
1623
Schickard described a machine with toothed wheels that added and subtracted, and carried from one wheel to the next, in letters to the astronomer Johannes Kepler. The machine itself was lost; modern copies have been built from his sketches.
Why it mattered. It is the earliest known design of a gear-driven calculator, though it had little influence at the time.
1642
Aged about 19, Pascal built an adding machine to help his father, a tax official, with endless sums. Dials turned toothed wheels, and a clever weighted lever carried a 1 into the next wheel whenever a wheel passed 9. About 20 were made.
Why it mattered. Its automatic carry is the mechanical cousin of the carry that ripples through a binary adder.
1673
Leibniz showed a model of his stepped reckoner to the Royal Society in London in 1673. Its stepped drum, a cylinder with teeth of different lengths, let a machine multiply by adding over and over. Stepped drums drove calculating machines for the next 300 years.
Why it mattered. Multiplying by repeated, shifted addition is exactly how simple calculator chips multiply.
1703
Leibniz published his explanation of binary arithmetic, showing how any number can be written with only 0 and 1, and how to add and multiply that way.
Why it mattered. Every electronic calculator works in binary, because a switch has just two states.
1851
1851 (patented 1820)
Charles Xavier Thomas de Colmar patented his arithmometer in 1820, and from 1851 it was made and sold in numbers. Based on Leibniz's stepped drums, it was the first mechanical calculator strong and reliable enough for offices, insurers and banks, and was made until about 1915.
Why it mattered. Calculating machines stopped being curiosities and became office equipment.
1854
Boole published The Laws of Thought, an algebra where statements are either true or false and are combined with AND, OR and NOT.
Why it mattered. Boolean algebra is the maths of logic gates.
1887
Felt patented the Comptometer, a key-driven adding machine: pressing a key in a column added that digit at once, with no crank to turn. Skilled operators, many of them women, added long columns of figures astonishingly fast, and Comptometers stayed in offices until the 1970s.
Why it mattered. It made calculating a matter of pressing keys, the way we still use calculators today.
1948
The Curta, a hand-cranked mechanical calculator small enough to hold in one hand, went on sale. Herzstark had worked out its design while a prisoner in the Buchenwald concentration camp.
Why it mattered. It was the best pocket calculator in the world until electronic ones arrived in the early 1970s.
1937 – 1967
Shannon shows switches can do logic. Relays, then vacuum tubes, then transistors replace gears, but calculators still weigh as much as a person.
1937
In his master's thesis, Shannon showed that circuits of relays and switches can carry out Boole's algebra, and so can add binary numbers. It was published in 1938.
Why it mattered. It is the idea behind every logic gate and adder in a calculator chip.
1959
Volder published CORDIC, a way to find sines, cosines and other functions with nothing but shifts, adds and a small table of angles. It was invented for aircraft navigation computers.
Why it mattered. Scientific calculators, starting with the HP-35, used this kind of shift-and-add method for trigonometry.
1961
October 1961
The ANITA Mk VII and Mk VIII were shown at the Business Efficiency Exhibition in London in October 1961. They used vacuum tubes and cold-cathode tubes instead of gears, with glowing Nixie tubes for digits. For over two years they were the only electronic desktop calculators in the world.
Why it mattered. Calculating became silent and electronic.
1964
Sharp's Compet CS-10A used 530 germanium transistors and 2,300 diodes. It weighed 25 kg and cost 535,000 yen, about as much as a car. The Friden EC-130 of 1963 was another early transistor calculator.
Why it mattered. Transistors replaced tubes, starting the race to make calculators smaller and cheaper.
1967 – 1978
Integrated circuits shrink calculators into the hand. A calculator chip becomes the first microprocessor, and LCDs cut power a hundredfold.
1967
Texas Instruments built a battery-powered prototype, code-named Cal Tech, about 4 × 6 × 2 inches and 45 ounces, with its logic on a few integrated circuits. It printed answers on paper tape. The team applied for a patent in September 1967.
Why it mattered. It proved a whole calculator could be built from chips and held in the hand.
1971
15 November 1971
The Japanese company Busicom asked Intel for chips for its 141-PF printing calculator. Intel's team put the calculator's processor on one chip, the 4004, with 2,300 transistors, running at up to 740 kHz. It was announced on 15 November 1971.
Why it mattered. The first commercial microprocessor was made for a calculator, which is why calculators are the stepping stone to computers.
1972
January 1972
The HP-35 was the first handheld scientific calculator, with sine, cosine, tangent, logarithms and powers. It cost $395, weighed about 260 g and used CORDIC-style shift-and-add routines. Slide rules started to disappear.
Why it mattered. It put a scientist's desk calculator in a shirt pocket.
1973
15 May 1973
Sharp's EL-805 was the first product on the market to use a liquid crystal display. Earlier calculators used glowing LEDs or tubes; the LCD cut power to about a hundredth, so the EL-805 ran about 100 hours on one AA battery.
Why it mattered. LCDs made calculators small, cheap and able to run for years on tiny cells.
By the numbers
In 15 years electric calculators went from the weight of two people to less than a bar of chocolate.
1976 – today
Solar cells, graphing screens and cheap chips put calculators everywhere, from shops to exam halls.
1978
Sharp's EL-8026 of 1976 used a solar cell to recharge its batteries. The Teal Photon of 1978 was among the first calculators to run on light alone, but needed bright light. Scientific solar calculators followed in 1982.
Why it mattered. CMOS chips and LCDs had cut power so far that a small solar cell was enough.
1985
Casio's fx-7000G could draw graphs of functions on a small dot-matrix screen and run short programs.
Why it mattered. Calculators became small programmable computers.
1994
A maths professor found that Intel's Pentium chip sometimes divided wrongly, from the fifth significant digit on, because a few entries were missing from a lookup table inside the chip. 4,195,835 ÷ 3,145,727 came out as 1.333739… instead of 1.333820… Intel replaced chips and took a $475 million charge.
Why it mattered. Even a tiny error in arithmetic hardware can be very costly, so chips are now checked with mathematical proofs.
2025
2024–25
Indian school board exams have long barred calculators, except for some students with special needs, so generations learned to work sums by hand. In a governing body meeting in December 2024, CBSE decided to allow basic, non-programmable calculators in the Class 12 Accountancy exam from the 2025–26 session, as reported in the press. Rules differ between boards.
Why it mattered. Deciding when a calculator helps learning, and when it gets in the way, is still a live question in classrooms.
Did you know?
The first commercial microprocessor, the Intel 4004 of 1971, was designed for a Japanese desk calculator, the Busicom 141-PF.
Casio's first calculator, the 14-A of 1957, used 342 relays and weighed about 140 kg.
Sharp's CS-10A of 1964 cost 535,000 yen, about as much as a car, and all 300 of the first batch sold out within months.
An LED calculator like the 1972 Sinclair Executive used about 20 mW; a modern Casio scientific calculator lists 0.0001 W, 200 times less.
On an 8-digit calculator with no hidden digits, 1 ÷ 3 × 3 gives 0.9999999.
The people
c. 598 – c. 668 · Mathematician and astronomer · India
Wrote the first known rules for calculating with zero and negative numbers.
1623 – 1662 · Mathematician and philosopher · France
Built an adding machine with an automatic carry while still a teenager.
1646 – 1716 · Mathematician and philosopher · Germany
Invented the stepped drum and explained binary arithmetic.
1862 – 1930 · Inventor and businessman · USA
Invented the key-driven Comptometer.
1916 – 2001 · Mathematician and engineer · USA
Showed that switching circuits can do logic and arithmetic.
1925 – 2018 · Inventor, co-founder of Casio · Japan
Designed Casio's relay calculator 14-A with his brothers.
1923 – 2005 · Engineer, Texas Instruments · USA
Co-invented the integrated circuit and led the Cal Tech handheld calculator project.
born 1943 · Engineer, Busicom and Intel · Japan
Worked out the logic of the Busicom calculator chips that became the Intel 4004.
born 1941 · Physicist and chip designer, Intel · Italy
Led the chip design of the Intel 4004.
Where it happened
Sources
Dates marked “c.” are approximate, and historians sometimes disagree about who was first. If you spot a mistake, tell us.
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