I went to IKEA today and found this: the UPPDATERA for 5 USD. It looks like it is intended for knife storage, but look how well it works to keep a few Slide Rules handy at your desk! #sliderules#sliderule
A paper slide rule to calculate fourth from three known variables: upper confidence limit, confidence level, number of observations, and number of events with a specified characteristic.
392 years ago, the English mathematician and clergyman William Oughtred introduced the multiplication sign ✕ for the first time. via @fermatslibrary.
Oughtred was the first to use logarithmic scales and sliding by one another to perform direct multiplication and division. He is credited with inventing the slide rule in about 1622. He also introduced the abbreviations "sin" and "cos" for the sine and cosine functions. via @wikipedia
@gutenberg_org@wikipedia
I am glad to know who is responsible for these #math concepts I take for granted. I got my first #calculator in 7th grade. Our math #teacher warned us not to rely on #calculators because "Sometimes they're wrong!" One of my #CivilEngineering#professors used a #SlideRule to show the importance of understanding the quantities we're working with rather than blindly accepting the results from a #computer. One #typo can lead to disaster. I now have my own slide rule.