Education and demonstration – Mathematics – Arithmetic
Patent
1986-12-22
1987-12-22
Grieb, William H.
Education and demonstration
Mathematics
Arithmetic
G09B 1902
Patent
active
047144297
ABSTRACT:
An educational device comprises an outer cylinder and an inner cylinder within said outer cylinder. The inner cylinder has an end extending from the outer cylinder and is rotatable and axially movable with respect to the outer cylinder. The inner cylinder has a series of multipliers (for example) peripherally arrayed around the end extending from the outer cylinder. The outer cylinder includes a series of windows and a series of multiplicands peripherally arrayed around the end from which the inner cylinder extends such that each of the multiplicands can be aligned with each of the multipliers by rotating one of the cylinders. The inner cylinder further includes rows of products physically arranged relative to the windows so that the products do not appear in the windows when the inner cylinder extends from said outer cylinder but do appear in the windows when said inner cylinder is inserted into said outer cylinder so as to display the product of the selected multiplier and multiplicand.
REFERENCES:
patent: 463230 (1891-11-01), Hooly
patent: 731175 (1903-06-01), Goodman
patent: 924406 (1909-06-01), Walker
patent: 969429 (1910-09-01), Warfield
patent: 2158431 (1939-05-01), Sanders
patent: 2533569 (1950-12-01), Espinola
patent: 2591327 (1952-04-01), Witter et al.
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