An image of this tool is shown below Stepped Reckoner or Leibnitz wheel A series of windows is given on the top of the wheels to read the totals.

When a wheel is rotated one revolution, it rotates the neighboring wheel.

It was a wooden box with a series of gears and wheels. It could only perform addition and subtraction. Pascal invented this machine to help his father, a tax accountant. It is believed that it was the first mechanical and automatic calculator. It was invented between 16 by a French mathematician-philosopher Biaise Pascal. Pascaline is also known as Arithmetic Machine or Adding Machine. It was also the first machine to use the decimal point. So, the tool became known as 'Napier's Bones. In this calculating tool, he used 9 different ivory strips or bones marked with numbers to multiply and divide. It was a manually-operated calculating device which was invented by John Napier (1550-1617) of Merchiston. An image of this tool is shown below Napier's Bones Abacus is still used in some countries like China, Russia and Japan. The beads were moved by the abacus operator according to some rules to perform arithmetic calculations.

It was a wooden rack which has metal rods with beads mounted on them. It is said that Chinese invented Abacus around 4,000 years ago. The history of computer begins with the birth of abacus which is believed to be the first computer. Some of the popular computing devices starting with the first to recent ones are described below Abacus As human mind and technology improved with time more computing devices were developed. They used sticks, stones and bones as counting tools. The first counting device was used by the primitive people.

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