巧算24点能用几种方法,4,5,6,7,小学数学.

1:4 × (5 - 6 + 7)
2:4 × ((5 - 6) + 7)
3:4 × (5 - (6 - 7))
4:4 × (5 + 7 - 6)
5:4 × ((5 + 7) - 6)
6:4 × (5 + (7 - 6))
7:4 × (7 + 5 - 6)
8:4 × ((7 + 5) - 6)
9:4 × (7 + (5 - 6))
10:4 × (7 - 6 + 5)
11:4 × ((7 - 6) + 5)
12:4 × (7 - (6 - 5))
13:(5 - 6 + 7) × 4
14:((5 - 6) + 7) × 4
15:(5 - (6 - 7)) × 4
16:(5 + 7 - 6) × 4
17:((5 + 7) - 6) × 4
18:(5 + (7 - 6)) × 4
19:(5 + 7) × (6 - 4)
20:(6 - 4) × (5 + 7)
21:(6 - 4) × (7 + 5)
22:(7 + 5 - 6) × 4
23:((7 + 5) - 6) × 4
24:(7 + (5 - 6)) × 4
25:(7 + 5) × (6 - 4)
26:(7 - 6 + 5) × 4
27:((7 - 6) + 5) × 4
28:(7 - (6 - 5)) × 4