The Slide Rule

The slide rule was developed in the 17th century and was in wide use until the second half of the 20th century. Simple slide rules support calculations with the precision of 2-3 significant digits, while some exotic models (typically helical scales on the side of a cylinder) support calculations with up to 5 significant digits.

The simulator of a basic slide rule (Pickett 160-ES Microline) shown below was created by Derek Ross (code and images, used with permission) using a freeware drag-and-drop javascript library by Walter Zorn. This simulator may not work on mobile platforms.