1975-12-03
1976-12-28
Skogquist, Harland S.
35 70, G09B 1902
Patent
active
039993108
ABSTRACT:
A plurality of rectangular blocks are juxtaposed in a rectangular coordinate ordered array to define a generally planar exposed surface with the opposite surface of the blocks attached to a flexible backing which functions as a hinge to allow a linear array of blocks to be pivoted parallel to a rectangular coordinate and expose indicia on the juxtaposed surfaces of the linear array, the indicia being related to other indicia on the exposed surface of the array such as the product of multiplying the two numbers along coordinate edges of the array.
REFERENCES:
patent: 3487578 (1970-01-01), Sudermann
patent: 3550310 (1970-12-01), Bock-Greissau
patent: 3628261 (1971-12-01), Thompson
patent: 3836418 (1974-09-01), Montgomery
Lufkin James Alan
Peterson Paul E.
Skogquist Harland S.
Tipton Robert R.
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