Have you ever been to Japan? Just walk through the streets and enter any souvenir shop and buy a few items, to your shock the shopkeeper will take out a traditional soroban and calculate your purchases instead of a calculator. You might think this to be a crazy behavior.
There are many people who are as comfortable to calculate as you do in a calculator. It is often we who underestimate the power of a primitive looking device and go for the electronic calculator. We can consider both as the different ends of a spectrum; both have their own advantages and disadvantages. It is quite strange to know that the modern day electronic calculator we see today had developed from a very similar algorithm of an abacus.
Perhaps abacus is the first accurate calculating machine that we knew. We all know that we had plenty of things to calculate before the invention of the electronic calculator. The invention of electronic calculator was only like an electronic aided device, which could give us the solution in a roundabout time without any mental application.
On the other hand the abacus is purely a mechanical device and it is assured that it would never fail or go wrong unless you do something wrong with it. The invention of the electronic calculator that you see today is not a one day affair. In fact we can say that the electronic calculators of today have evolved from the abacus and the various concepts used in abacus.
Long before the electronic calculators were thought of, a variety of types of abacus were developed, but the most popular became those based on the bi-quinary system, which utilizes a combination of two bases i.e base-2 and the base-5 system to represent decimal numbers. These were considered as the scientific calculators of those days.
Although the abacus does not qualify as a mechanical calculator, it certainly stands proud as one of first mechanical aids to calculation and if you know how to master an abacus then you can even out beat a modern calculator in terms of accuracy and speed.