| 序号 | 题目:4,6,9,13 | |
|---|---|---|
| 1 | ((9 + 6) + 13) − 4 | |
| 2 | ((13 − 4) + 6) + 9 | |
| 3 | ((13 + 9) + 6) − 4 | |
| 4 | ((13 + 9) − 4) + 6 | |
| 5 | ((13 + 6) + 9) − 4 | |
| 6 | ((13 + 6) − 4) + 9 | |
| 7 | (13 + (9 − 4)) + 6 | |
| 8 | (13 + 9) + (6 − 4) | |
| 9 | (9 + (13 − 4)) + 6 | |
| 10 | (13 + (6 − 4)) + 9 | |
| 11 | (9 + 6) + (13 − 4) | |
| 12 | (13 + 6) + (9 − 4) | |
| 13 | 13 + ((9 + 6) − 4) | |
| 14 | 13 + (6 + (9 − 4)) | |
| 15 | 13 + (9 + (6 − 4)) | |