Since the beginning of time there has been a need for oneself to keep track of ones trading transactions by applying some method to calculate in a fair and accurate manner. Merchants trading goods not only needed a way to count goods bought and sold but also to quickly the cost of goods.
By this essential need, the pressure of having a standard method that everyone will abide and understand, the abacus was used. This emerged about 5000 years ago in Asia Minor and this could be considered the first computer. The abacus was used as a mechanical aid, used for counting. The person actually performing the calculations did it in their head and the abacus was used just to keep track of the sums, the carries and so on.
The next significant step forward came about 12 centuries later. In 1642 Blaise Pascal (1623 - 1662), the 18-year-old son of a tax collector invented what he called a numerical wheel calculator in order to help his father with his taxation duties. It was made of brass and was also known as the Pascaline. It used eight dials to add numbers eight digits long. It worked on base ten, as 1 dial moved ten notches or 1 complete revolution, the next dial will move a notch. Obviously limitation of this machine was only addition could be done. However in1694, a German mathematician, Gottfried Wilhem Von Leibniz (1646-1716), made a significant improvement on Pascal's machine. Leibniz made a machine that could also multiply and worked on a system of dials and gears. The centrepiece of Leibniz's machine was its stepped-drum gear.
It wasn't until 1820 when a Frenchman, Charles Xavier Thomas de Colmar invented a mechanical calculator (the arithometer) that add, subtract, multiply and divide. It proved to be very popular as now people found it easier to calculate. This invention was used up to the First World War.
However some past historians have stated that the real beginnings came with Charles Babbage (1791 - 1871).