There have been many attempts at improving the methods we use for calculations. One of the longest lasting devices is the abacus.

**The Abacus**

An abacus is a manual aid to calculating that consists of beads or disks that can be moved up and down on a series of sticks or strings within a usually wooden frame. It has existed since Roman times and has been used by many civilizations. It is still used as a major calculating device in many Asian Countries.

The abacus itself doesn’t calculate; it’s simply a device for helping to calculate by remembering what has been counted. The modern Chinese abacus dates from about 1200 A.D. It is possible that it derives from the earlier counting board s used around the Mediterranean as early as 300 B. C. An Aztec version of an abacus, circa 900-1000 A.D., is made from maize threaded through strings mounted in a wooden frame.

**Napier’s Bones**

The Scottish mathematician and inventor, John Napier discovered a method for assisting multiplications by having a set of times tables, which he inscribed on, whale bone. Napier’s bones were tables written on strips of wood or bones. The invention was used for multiplying, dividing, and taking square roots and cube roots.

**The Slide Rule**

Englishman William Oughtred invented the Slide rule in 1622. The slide rule is a mechanical analog computer, which is used primarily for multiplication and division, and also for functions such as roots, logarithms and trigonometry. It is not normally used for addition or subtraction. The slide rule is not ordinarily used for measuring length or for drawing straight lines.

Slide rules come in a diverse range of styles and generally appear in a linear or circular form with a standardized set of scales essential to performing mathematical computations.

Before the advent of the pocket calculator, it was the most commonly used calculation tool in science and engineering but around 1974 the electronic scientific calculator made it largely obsolete.

**Pascal’s calculating device**

The French mathematician Blaise Pascal created the first mechanical calculating device. It used a set of cogs and was capable of addition. In 1642, at the age of 18, Pascal invented and build the first digital calculator as a means of helping his father perform tedious tax accounting. The device was called Pascal’s calculator or the Pascaline or the Arithmetique. Pascal continued to make improvements to his design through the next decade and built fifty Pascaline machines in total.