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Priority to NL7203265ApriorityCriticalpatent/NL7203265A/xx
Publication of NL7203265ApublicationCriticalpatent/NL7203265A/xx
G09B—EDUCATIONAL OR DEMONSTRATION APPLIANCES; APPLIANCES FOR TEACHING, OR COMMUNICATING WITH, THE BLIND, DEAF OR MUTE; MODELS; PLANETARIA; GLOBES; MAPS; DIAGRAMS
G09B19/00—Teaching not covered by other main groups of this subclass
G09B19/02—Counting; Calculating
G—PHYSICS
G06—COMPUTING OR CALCULATING; COUNTING
G06C—DIGITAL COMPUTERS IN WHICH ALL THE COMPUTATION IS EFFECTED MECHANICALLY
G06C1/00—Computing aids in which the computing members form at least part of the displayed result and are manipulated directly by hand, e.g. abacuses or pocket adding devices