| 摘要 |
An abacus whereby the number represented thereon is also shown in digital form is disclosed. It consists of columns of figures (5 to 7) behind windows (2 to 4) on the front. The number of figures displayed in each column can be controlled by manipulating sliding covers (8 to 10) up and down. The number of figures displayed on the front is displayed in digital form (31 and 32) in windows (33 to 35) on the back. |
