20以内退位减法表如下：
| 被减数 | 减数 | 结果 |
| --- | --- | --- |
| 10 | 9 | 1 |
| 11 | 9 | 2 |
| 12 | 9 | 3 |
| 13 | 9 | 4 |
| 14 | 9 | 5 |
| 15 | 9 | 6 |
| 16 | 9 | 7 |
| 17 | 9 | 8 |
| 18 | 9 | 9 |
| 19 | 9 | 10 |
| 11 | 8 | 3 |
| 12 | 8 | 4 |
| 13 | 8 | 5 |
| 14 | 8 | 6 |
| 15 | 8 | 7 |
| 16 | 8 | 8 |
| 17 | 8 | 9 |
| 18 | 8 | 10 |
| 19 | 8 | 11 |
| 11 | 7 | 4 |
| 12 | 7 | 5 |
| 13 | 7 | 6 |
| 14 | 7 | 7 |
| 15 | 7 | 8 |
| 16 | 7 | 9 |
| 17 | 7 | 10 |
| 18 | 7 | 11 |
| 19 | 7 | 12 |
| 11 | 6 | 5 |
| 12 | 6 | 6 |
| 13 | 6 | 7 |
| 14 | 6 | 8 |
| 15 | 6 | 9 |
| 16 | 6 | 10 |
| 17 | 6 | 11 |
| 18 | 6 | 12 |
| 19 | 6 | 13 |
| 11 | 5 | 6 |
| 12 | 5 | 7 |
| 13 | 5 | 8 |
| 14 | 5 | 9 |
| 15 | 5 | 10 |
| 16 | 5 | 11 |
| 17 | 5 | 12 |
| 18 | 5 | 13 |
| 19 | 5 | 14 |
| 11 | 4 | 7 |
| 12 | 4 | 8 |
| 13 | 4 | 9 |
| 14 | 4 | 10 |
| 15 | 4 | 11 |
| 16 | 4 | 12 |
| 17 | 4 | 13 |
| 18 | 4 | 14 |
| 19 | 4 | 15 |
希望这些信息对你有所帮助。