|Persona:||Prusmack, Murray (P)|
|Link interni:||Rechenschieber, ABA-Ten Rule, Lehrmittel|
|Link al brevetto:|
|US3147556 (espacenet), US3147556 (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.
- DATUM: 08.09.1964
- TITEL: Calculating device