Education and demonstration – Mathematics – Arithmetic
Patent
1979-08-27
1981-05-26
Grieb, William H.
Education and demonstration
Mathematics
Arithmetic
G09B 1902
Patent
active
042695970
ABSTRACT:
An educational device for training in arithmetic utilizing rotatably mounted hand like members which simulate a pair of hands which exhibit a selected numeral on each finger like portion of each hand. Each finger like portion of each hand member is alignable with a finger like portion of the other hand member and with a reference line. In an arcuate area below the reference line and under each hand like portion is disposed a row of tens which are circumferentially aligned with a row of five apertures on each hand like member with each aperture being aligned with a single finger like portion on each hand like member.
Adapters are provided for covering the numerals of each of the finger like portions and displaying a numeral which is a multiple of the numeral appearing on each of the finger like portions respectively. Adapters are also provided for covering each of the arcuate portions and displaying two rows of numerals corresponding to twice said multiple of tens. The mathematical operation which now yields the product of the numbers appearing on the aligned finger like portions comprises multiplying the multiple of the number of fingers above the reference line and adding to the resulting number said multiple of the sum of numbers appearing through the apertures of the hand like portions below the reference line.
REFERENCES:
patent: 1457223 (1923-05-01), Gallup
patent: 1548601 (1925-08-01), Hoeft
patent: 1581390 (1926-04-01), Cook
patent: 2471271 (1949-05-01), Green
patent: 2792993 (1957-05-01), Schramm
Grieb William H.
Michalos Constantine A.
Michalos Peter C.
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