Calculation tools emerged in countless early cultures. Numbers were ‘saved’ and ‘modified’ by moving beads in an abacus or making knots in ropes.

British mathematician Charles Babbage built a number of what were known as difference engines in the first half of the nineteenth century. He wanted to use them to quickly calculate the outcomes of a mathematical function.

The difference engines used a huge amount of cog wheels to do a series of additions. But Babbage was unable to get his machines working. It was not until the year 1991 that a replica proved that the mechanism did in fact work.

Mechanical desk calculator (1955) by Antares**NEMO Science Museum**

In 1851, arithmometers appeared on the market that were able to add, subtract, multiply and divide.

This machine is called the Antares P2 and appeared later, but works in a comparable way with cog wheels that make a specific number of turns, producing the results.

Entering the settings may take a little while, but after that the sum 255 x 31 is literally done with the flip of a switch.

Mechanical desk calculator (1943) by Brunsviga**NEMO Science Museum**

Calculators were cumbersome and heavy.

This German-made Brunsviga 20 was sold from the 1930s on and weighed 12 kilos.

Brunsviga calculating machine (1905) by Nerenz**Original Source: https://de.wikipedia.org/w/index.php?title=Datei:Rechenmaschine_Brunsviga_1905.JPG&filetimestamp=20080309194118&**

The ad for the Brunsviga calculator claims it ‘never miscalculates’.

The device was praised as a great option to calculate taxes and wages.

Manufacturers developed various types of machines. This product by Facit used buttons to enter the numbers, but the mechanical system on the inside looked a lot like the previous calculators.

A so-called comptometer was able to calculate large numbers quickly. That was its only use too. The sum 123 x 9 could be calculated by pressing the buttons 1, 2 and 3 nine times at the same time.

To speed up calculations, electric machines were created, such as this one by Monroe. A motor drives the calculation mechanism, that in itself is fully mechanical.

Some institutes – such as the NASA space organization – were in dire need of calculation power and hired human calculators. These hires calculated rocket trajectories for example. This was common practice until the 1970s.

Electric calculator by Burroughs**NEMO Science Museum**

Over the course of the 1950s, due to innovations of the gears, calculators became smaller and smaller.

These Burrough calculators were able to multiply numbers and print the results on paper immediately.

Scientific electronic pocket calculator by Hewlett Packard**NEMO Science Museum**

In the 1970s, more compact and fully electronic calculators emerged with a digital display.

This model issued by Hewlett Packard in 1973 still needed to be plugged in and was intended to make scientific calculations.

Various electronic pocket calculators by Unknown**NEMO Science Museum**

Nowadays people mostly use their mobile phones or computers for calculations

Abacuses, mechanical and even electronic calculators are now mostly found in museums.

Credits: Story

**Object of the Month – October 2021 **

Each month, NEMO Science Museum spotlights one item from its collection of 19,000 special objects. These objects, which were once part of people’s everyday lives, show us how technology changes over time.

Credits: All media

The story featured may in some cases have been created by an independent third party and may not always represent the views of the institutions, listed below, who have supplied the content.

Stories from NEMO Science Museum

Google apps