1,2,4,7算出24点

4*(（7-2)+1)

4的2次方+7+1=24

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