算24点(4 7 8 9)

1:4 × (7 + 8 - 9)
2:4 × ((7 + 8) - 9)
3:4 × (7 + (8 - 9))
4:4 × (7 - 9 + 8)
5:4 × ((7 - 9) + 8)
6:4 × (7 - (9 - 8))
7:4 × (8 + 7 - 9)
8:4 × ((8 + 7) - 9)
9:4 × (8 + (7 - 9))
10:(4 + 8) × (9 - 7)
11:4 × (8 - 9 + 7)
12:4 × ((8 - 9) + 7)
13:4 × (8 - (9 - 7))
14:(7 + 8 - 9) × 4
15:((7 + 8) - 9) × 4
16:(7 + (8 - 9)) × 4
17:(7 - 9 + 8) × 4
18:((7 - 9) + 8) × 4
19:(7 - (9 - 8)) × 4
20:(8 + 4) × (9 - 7)
21:(8 ÷ (7 - 4)) × 9
22:8 ÷ (7 - 4) × 9
23:8 ÷ ((7 - 4) ÷ 9)
24:(8 + 7 - 9) × 4
25:((8 + 7) - 9) × 4
26:(8 + (7 - 9)) × 4
27:(8 - 9 + 7) × 4
28:((8 - 9) + 7) × 4
29:(8 - (9 - 7)) × 4
30:8 × (9 ÷ (7 - 4))
31:8 × 9 ÷(7 - 4)
32:(8 × 9) ÷ (7 - 4)
33:(9 - 7) × (4 + 8)
34:(9 ÷ (7 - 4)) × 8
35:9 ÷ (7 - 4) × 8
36:9 ÷ ((7 - 4) ÷ 8)
37:(9 - 7) × (8 + 4)
38:9 × (8 ÷ (7 - 4))
39:9 × 8 ÷(7 - 4)
40:(9 × 8) ÷ (7 - 4)