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