| 序号 | 题目:1,3,9,13 | |
|---|---|---|
| 1 | ((13 − 1) + 9) + 3 | |
| 2 | ((13 + 9) − 1) + 3 | |
| 3 | ((13 + 9) + 3) − 1 | |
| 4 | ((13 − 1) + 3) + 9 | |
| 5 | ((13 + 3) − 1) + 9 | |
| 6 | ((13 + 3) + 9) − 1 | |
| 7 | (13 + (3 − 1)) + 9 | |
| 8 | (13 − 1) + (9 + 3) | |
| 9 | (13 + 9) + (3 − 1) | |
| 10 | (13 + 3) + (9 − 1) | |
| 11 | (13 + (9 − 1)) + 3 | |
| 12 | (9 + 3) + (13 − 1) | |
| 13 | (13 + (9 + 3)) − 1 | |
| 14 | 13 + ((9 + 3) − 1) | |
| 15 | 13 + (9 + (3 − 1)) | |
| 16 | 13 + ((9 − 1) + 3) | |