| 摘要 |
An educational device is described for teaching arithmetical operations which comprises: a graph-like base member having a set of four symbols positioned in the upper region thereof, namely, a division symbol, a multiplication symbol, a subtraction symbol and a downwardly pointing arrow. A plurality of movable members are applied onto the graph-like base member and have depicted on at least one main surface thereof such indicia as numerals from 0 through 9, preselected letters of the alphabet, punctuation symbols or mathematical process signs. Several horizontal separation bars of predetermined length and having a width equal to at least about one-third the width of the movable members are employed; at least one of these separation bars is longer then the others and has an L-shaped configuration. A plurality of arrow-like members of varied length and of width substantially equal to the width to the horizontal bars completes the components of the educational device of the invention.
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