1,2,4,7算出24点

1, 2, 4, 7的24点答案：
1:(1 - 2 + 7) × 4
2:((1 - 2) + 7) × 4
3:(1 - (2 - 7)) × 4
4:(1 + 4 + 7) × 2
5:((1 + 4) + 7) × 2
6:(1 + (4 + 7)) × 2
7:(1 + 7 - 2) × 4
8:((1 + 7) - 2) × 4
9:(1 + (7 - 2)) × 4
10:(1 + 7 + 4) × 2
11:((1 + 7) + 4) × 2
12:(1 + (7 + 4)) × 2
13:2 × (1 + 4 + 7)
14:2 × ((1 + 4) + 7)
15:2 × (1 + (4 + 7))
16:2 × (1 + 7 + 4)
17:2 × ((1 + 7) + 4)
18:2 × (1 + (7 + 4))
19:2 × (4 + 1 + 7)
20:2 × ((4 + 1) + 7)
21:2 × (4 + (1 + 7))
22:2 × (4 + 7 + 1)
23:2 × ((4 + 7) + 1)
24:2 × (4 + (7 + 1))
25:2 × (7 + 1 + 4)
26:2 × ((7 + 1) + 4)
27:2 × (7 + (1 + 4))
28:2 × (7 + 4 + 1)
29:2 × ((7 + 4) + 1)
30:2 × (7 + (4 + 1))
31:4 × (1 - 2 + 7)
32:4 × ((1 - 2) + 7)
33:4 × (1 - (2 - 7))
34:(4 + 1 + 7) × 2
35:((4 + 1) + 7) × 2
36:(4 + (1 + 7)) × 2
37:4 × (1 + 7 - 2)
38:4 × ((1 + 7) - 2)
39:4 × (1 + (7 - 2))
40:(4 + 7 + 1) × 2
41:((4 + 7) + 1) × 2
42:(4 + (7 + 1)) × 2
43:4 × (7 + 1 - 2)
44:4 × ((7 + 1) - 2)
45:4 × (7 + (1 - 2))
46:4 × (7 - 2 + 1)
47:4 × ((7 - 2) + 1)
48:4 × (7 - (2 - 1))
49:(7 + 1 - 2) × 4
50:((7 + 1) - 2) × 4
51:(7 + (1 - 2)) × 4
52:(7 + 1 + 4) × 2
53:((7 + 1) + 4) × 2
54:(7 + (1 + 4)) × 2
55:(7 - 2 + 1) × 4
56:((7 - 2) + 1) × 4
57:(7 - (2 - 1)) × 4
58:(7 + 4 + 1) × 2
59:((7 + 4) + 1) × 2
60:(7 + (4 + 1)) × 2