Patent:US3147556

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Brevetto:US 3147556
Titolo:Calculating Device
Data:08.09.1964
Luogo:
Nazione:Stati Uniti
Persona:Prusmack, Murray (P)
Ditta:
Link interni:Rechenschieber, ABA-Ten Rule, Lehrmittel
Keywords:slide rule
Link al brevetto:
(without guarantee)
 US3147556 (http://v3.espacenet.com/textdoc?DB=EPODOC&F=0&IDX=US3147556) (espacenet),  US3147556 (http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/FPTO/srchnum.htm&r=1&f=G&l=50&s1=3147556.PN.&OS=PN/3147556&RS=PN/3147556) (uspto)


"This invention relates to teaching aids and more particularly to a new and useful calculating device for introducing children of the kindergarten and lower grammar school grades to basic concepts in various branches of mathematics.

It is a primary object of present coordinates the sense of touch with the sense of sight to physically present and demonstrate a variety of basic number groupings in the arts of addition, subtraction, multiplication, and division and the number facts of these groupings in a manner which assists the young student in correlating abstract numerical symbols with corresponding physical entities." Aus der Patentschrift.

aus der Patentschrift

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Ultima modifica il 16:59, 18. Ott 2007.