在线算24点

1: (1 + 2) × 2 × 4 2: ((1 + 2) × 2) × 4 3: (1 + 2) × (2 × 4) 4: (1 + 2) × 4 × 2 5: ((1 + 2) × 4) × 2 6: (1 + 2) × (4 × 2) 7: (2 + 1) × 2 × 4 8: ((2 + 1) × 2) × 4 9: (2 + 1) × (2 × 4) 10: (2 × (1 + 2)) × 4 11: 2 × (1 + 2) × 4 12: 2 ×