| 摘要 |
<p>. A teaching aid for multiplication tables, the aid comprising a tubular sleeve (5) with a cylindrical member (1) rotatably mounted in the sleeve (5). Two longitudinally oriented adjacent parallel rows of holes (9 and 10) in the sleeve (5) with a row of multiplicands marked on the sleeve (5) and positioned between the rows of holes (9 and 10) and respectively aligned therewith. The cylindrical member (1) has parallel rows of multiplier numerals and product numerals marked thereon with spacings between the rows ensuring that the products of numerals appearing in one row of holes (10) multiplied by the aligned multiplicands will appear in the holes (9) of the other row of holes.</p> |
