The slide rule was used for over 400 years as a calculating/estimation tool. Abandoned with the advent of hand-held calculators, computers and smart phones, their elegant simplicity is still a thing of wonderment. This program replicates the most common types of slide rules: Straight, circular, spiral and cylindrical. Dozens of scales are included and numerous features that could never exist on a physical slide rule are also included, such as color options, numeric displays of the values unde