How long have we as a species needed to count and calculate numbers? Probably as long as our species have existed. So how did we do it back then? Well, let’s take a rather brief look at how the art of calculating has evolved over the years from fingers and pebbles to advanced computers that can perform complex calculations in split seconds. Fingers and pebbles? Well, that has to be the earliest way anyone ever calculated anything. However, the history of calculators — and by this term I do refer to any equipment or machine that makes it easier and faster to perform rather complex calculations — really begins somewhere around 2,500 to 2,000 BCE with the invention of *the Abacus* which was first used in Sumeria (now Iraq) and Egypt. It was a wooden frame with slide-able beads on horizontal rods.

Several centuries later, in the 17^{th} century, *Napier’s Bones* was invented. The bones were thin rods inscribed with multiplication tables and when the vertical alignment of the rods are adjusted, the user can read off his multiplication totals horizontally. Napier’s bones and the abacus remained in accountant’s offices even up to the 19^{th} century, even though other calculating inventions came up. It was in the same 17^{th} century that the *slide rule *was invented. It consisted of a sliding stick that could perform rapid multiplications by using logarithmic scales and it stuck around even up to the 1980’s as it was a pocket size calculating device. Blaise Pascal also invented his *Pascal’s Calculator* in 1642. The first of its kind, it was a device that performed all four arithmetic operations without relying on human intelligence. It used geared wheels, was considered truly ingenious but were difficult to produce and so only a few were ever made.

Then in 1850, Thomas de Colmar launched the four function *Arithmometer, *the first mechanical calculator that was considered robust enough for everyday use. His invention was followed by a proliferation of mechanical calculating machines that could perform all four of the arithmetic operations quickly and accurately. The biggest issue with all these devices was that they were usually large and heavy. This problem of size was solved with the invention of the* Curta Calculator* in 1948 by Curt Herzstark. It was a work of staggering ingenuity at the time, small enough to be held in the hand, able to perform all four arithmetic calculations quickly and accurately and some models could display 15-digit answers (a truly remarkable feet then, considering that an iPhone 6 Plus displays 16-digit answers in *scientific mode!*). It was the best and the last of the mechanical calculators.

As electronics began to take over, several types of calculators were developed starting with *ENIAC* (Electronic Numeric Integrator And Computer) in 1946, which was a thousand times faster than electro-mechanical computers but used almost 18,000 vacuum tubes, filled a large room and used as much power as a small town. As vacuum tubes gave way to thermionic valves and then to solid state transistors and finally to microchips, electronic calculators continued to be invented from the 1960’s through the 1970’s, each new product trying to better the previous ones in terms of size, power consumption, processing ability and cost. By 1980, pocket calculators had become compact in form, powered by solar cells or button batteries, had a wide variety of functions and were very cheap.

The 1980’s saw the advent of industry-specific calculators which were tailored towards the needs of their respective industries and could perform more advanced and complicated calculations. By the 1990’s, along with the prevalence of PCs and laptops, came the mobile phones which had calculator functions programmed into them. Phones have gotten smarter ever since and calculators have always been a part of mobile phones. On today’s smart phones, one can even get some of those highly specialized types of calculators as just an app in the phone. Despite this proliferation of smartphones with calculators, the ‘dumb’ calculator has not lost its relevance as it is still the choice of people who have to work with a lot of numbers daily and is the only type of computer allowed in most exam halls around the world.

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