## Mechanical Calculating Era:

The mechanical calculating devices were based on the counting principles. The were based on decimal number system.

## The Abacus:

An **abacus **is a manual counting tool that uses beads sliding on rods or wires within a frame. It has been used since ancient times for performing calculations such as addition and subtraction.

â€¢ It was invented in Babylonia by chinese in 300 BC.

â€¢ It is one of the oldest known calculating devices.

â€¢ It is divided into two parts by midbar as heaven and earth. There are 2 beads in heaven, each equivalent to 5 and there are 5 beads in earth, each equivalent to 1.

â€¢ Calculation is done by sliding the beads in both sections.

## Slide Rule:

A **slide rule** is a mechanical calculating device that uses logarithmic scales to perform multiplication, division, powers and roots.

â€¢ It was invented by English mathematician William Oughtred in 1622 AD.

â€¢ It was built on the work by Napier on logarithms.

â€¢ It consists of two rulers and a scale.

**How does a slide rule work?**

A slide rule is a long, narrow ruler with a series of logarithmic scales. The two main scales are the C and D scales, which are used for multiplication and division. The other scales on the slide rule are used for trigonometric functions, logarithms, and other calculations.

To perform multiplication, the user aligns the two numbers to be multiplied on the C and D scales. Then, the user slides the middle section of the slide rule to find the product.

To perform division, the user aligns the dividend on the C scale and the divisor on the D scale. Then, the user subtracts the divisor from the dividend on the C scale to find the quotient.

## Pascaline:

**Pascaline **is the first mechanical calculator.

â€¢ It was invented by Blaise Pascal in 1642 when he was only 18 years old to help his father with his duties, who was a french tax collector.

â€¢ The brass rectangular box also called as pascaline used 8 moveable dials to add sum.

â€¢ The drawback of pascaline of course was its limitation to addition only.

**How does Pascaline work?**

Pascaline is a mechanical calculator that uses a series of interlocking wheels to perform calculations. Each wheel has ten teeth, and each tooth represents a digit. To add two numbers, the user turns the corresponding wheels on the Pascaline. The wheels will rotate until the correct sum is displayed.