# It All Adds Up: The History of the Calculator

By | May 6, 2019

Since no one likes doing mental math, humans have devices ways of calculating numbers that require very little brain power. And it is a good thing they have! Where would we be without our handy calculators when we need to figure out how much to tip our servers, how much our overtime paycheck will be, or how much to pay the babysitter? The invention of the calculator that we all use today is the result of a long line of devices—from abacuses to slide rules—created to take the brain hurt out of math.

## The Abacus

We often consider the abacus to be a Chinese invention, but historians now believe that this early computation device was actually created in Sumeria around the year 2500 BC. The abacus worked by holding place values in columns of beads, pebbles, or shells. By manipulating the number of beads in each column, the user could make complex addition and subtraction calculations. The Chinese improved upon the concept by stringing the beads on wire columns in a frame to make it easier to use and more portable…good for merchants and tradesman. The biggest limitation to the abacus, however, is that it only works for addition and subtractions problems.

## Napier’s Bones

Despite its limitations, the abacus was the dominate calculation device for doing basic math. It took more than four thousand years before a better method was invented. In 1617, John Napier, a mathematician from Scotland, published his report on a method he developed that used rods as a means of calculating. His mathematical device, which came to be known as Napier’s Bones, was a series of rods on which the multiplication table was written. To make calculations, the user figured out the problem by changing the vertical positions of the rods. The answer was then shown horizontally.

## Blaise Pascal and the First True Calculator

While the abacus and Napier’s Bones were helpful in solving **math problems**, they were not true calculators. The invention of the first true calculator is credited to Blaise Pascal, a French mathematician, and inventor. Pascal’s invention used geared wheels to make the calculations. He designed his calculator so that each individual dial had all the single digit numbers on it. When the dial was turned to zero, the dial adjacent to it carried the 1. This allowed for faster and more complex calculations to be made. The biggest drawbacks to Pascal’s calculator, however, were that they were difficult and costly to produce and they were bulky and cumbersome.

## Thomas de Colmar’s Arithmometer

The Arithmometer, created by Thomas de Colmar in 1820, was the first reliable mechanical calculator. It was so accurate and well-built that it became a mainstay in 19th-century business offices and retail outlets. It used rotating drums to perform the calculations. In fact, it was the design that was exclusively used until the first few decades of the 20th century. Historians cite the Arithmometer as the invention that effectively ended the use of human calculators—smart, math-minded people who did the complex calculations for the rest of us. It also kicked off the mechanical calculator industry which continued strong until the 1970s.

## Handheld Calculators

In 1938, Curt Herzstark began tinkering with the workings of mechanical calculators to try and devise a handheld version. Finally, in 1945, he released his Curta calculators. These Curta calculators did not look like the portable calculators were would see in the seventies. In fact, it was shaped more like a large pepper grinder. But it was capable of doing the calculations that business people, students, and bankers needed and was portable enough to carry around.

## Electrical and Digital Calculators

The 1940s saw the creation of electrical calculators, but these machines were hampered by the large size of the vacuum tubes. Once the technology-enabled smaller vacuum tubes, electronic calculators really took off. But that all changed in the 1970s when the Japanese produced the first digital calculators. The microchip allowed these digital calculators to be pocket-sized and—very quickly—inexpensive. Within a decade, it was possible to get a credit card-sized digital calculator for just a few dollars.

## Smartphones

When the first smartphone was introduced in 1995, it was billed as more than a mobile phone. It was like having a tiny computer in your pocket, complete with all the tools you might need—a flashlight, camera, map, and of course, a calculator. Calculators have come a long way from the abacus and adding machines and thank goodness they have! Now we can split a restaurant check with a friend or figure out if 20% off is a good deal without having to strain our brains.