Esther's photos with the keyword: calculator

The slide rule was developed in the 17th century, but its modern version dates from the mid-1800's. It was eventually displaced by the pocket calculator starting in the late 1960's. However, it was still used on Apollo missions in the 1970's. Using the various scales on both sides, one could solve problems involving multiplication, division, square and cube roots, plane and hyperbolic trigonometry, logarithms, and numbers raised to a power. This particular slide rule, the Keuffel & Esser log log duplex vector, came with a 132 page manual (http://www.mccoys-kecatalogs.com/KEManuals/4081-3_1955/4081-3_1955.pdf) and a 49 page supplemental manual www.mccoys-kecatalogs.com/KEManuals/4083-3/4083manual.pdf . If you think that camera manuals are difficult to read, try a slide rule manual. The Sunday Challenge: Numbers AIMG 4523