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