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