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