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Do you know WolframAlpha?
A "computational knowledge engine that draws on multiple sources to answer user queries directly". A search within WolframAlpha generates output by doing computations from its own internal knowledge base. Some examples include: mathematics, statistical probabilities, conversions and calculations (electric circuit calculations), physics, and many more.
As a fun example enter 17 miles per gallon to metric to see how imperial can be easily converted.
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Middle East Technical University Library
Dumlupınar Bulvarı No:1
06800 Çankaya Ankara TÜRKİYE