Determining who invented the calculator and when the first calculator was created is not as easy as it seems. Even in pre-historic times, bones and other objects were used to calculate arithmetic functions. Long afterward came mechanical calculators, followed by electrical calculators and then their evolution into the familiar but not-so-ubiquitous-anymore handheld calculator.

Here, then, are some of the milestones and prominent figures who played a role in the development of the calculator through history.

### Milestones and Pioneers

**The Slide Rule: **Before we had calculators we had slide rules. In 1632, the circular and rectangular slide rule was invented by W. Oughtred (1574-1660). Resembling a standard ruler, these devices allowed users to multiply, divide, and calculate roots and logarithms. They were not typically used for addition or subtraction, but they were commonplace sights in school rooms and workplaces well into the 20^{th} century.

### Mechanical Calculators

**William Schickard (1592 - 1635): **According to his notes, Schickard succeeded in designing and building the first mechanical calculating device. Schickard’s accomplishment went unknown and unheralded for 300 years, until his notes were discovered and publicized, so it was not until Blaise Pascal’s invention gained widespread notice that mechanical calculation came to the public’s attention.

**Blaise Pascal (1623 - 1662):** Blaise Pascal invented one of the first calculators, called the Pascaline, to help his father with his work collecting taxes.

An improvement on Schickard’s design, it nevertheless suffered from mechanical shortcomings and higher functions required repetitive entries.

### Electronic Calculators

**William Seward Burroughs (1857 – 1898):** In 1885, Burroughs filed his first patent for a calculating machine. However, his 1892 patent was for an improved calculating machine with an added printer.

The Burroughs Adding Machine Company, which he founded in St. Louis, Missouri, went on to great success popularizing the inventor’s creation. (His grandson, William S. Burroughs enjoyed great success of a far different kind, as a Beat writer.)