A wise secondary school maths teacher would often have us bring out our crutches. We were only allowed to use them however when the problem infringed upon us was to intricate to decipher at our own merits.
This crutch as Mr G would call it is in fact a calculator.
I’ve always appreciated this metaphor as I feel it is completely appropriate. Even when completing simple additions and subtractions we reach for the calculator app on our phones. “Nowadays… people plug numbers into a calculator without any intuitive sense of whether the answer is correct.” (Bellos, 2010).
The standard electronic calculators we have today were by no means the first calculating devices. Abacus’ are thought to have been used from as early as 2700BC, they are often constructed as a bamboo frame with beads sliding on wires, but originally they were beans or stones moved in grooves in sand or on tablets of wood, stone or metal. (‘Abacus’,2016) 
Then came the Slide Rule “The Reverend William Oughtred and others developed the slide rule in the 17th century based on the emerging work on logarithms by John Napier. Before the advent of the electronic calculator, it was the most commonly used calculation tool in science and engineering. The use of slide rules continued to grow through the 1950s and 1960s even as digital computing devices were being gradually introduced; but around 1974 the handheld electronic scientific calculator made it largely obsolete and most suppliers left the business.” (‘Slide Rule’, 2016)
There were a variety of other calculating creations through time but many came to a standstill after the creation of the HP-35. Hewlett-Packard launched his creation in 1972, at the time these devices of 35 buttons and a red LED display would cost £365. By 1978 the electronic calculator was growing and was eventually priced under £5 making it accessible to the general public (Bellos, 2010).
References:
‘Abacus’ (2016) Wikipedia. Available at: https://en.wikipedia.org/wiki/Abacus (Accessed: 22 November 2016)
Bellos, A. (2010) Alex’s Adventures in Numberland. London; Bloomsbury.
‘Slide Rule’ (2016) Wikipedia. Available at: https://en.wikipedia.org/wiki/Slide_rule (Accessed: 22 November 2016)
