Keywords: Friden calculator - Ridai Museum of Modern Science, Tokyo - DSC07579.JPG en Exhibit in the Ridai Museum of Modern Science Tokyo University of Science Kagurazaka campus - 1-3 Kagurazaka Shinjuku-ku Tokyo 2015-02-20 02 10 12 own Daderot other versions cc-zero Mechanical calculators in the Ridai Museum of Modern Science Friden calculators |