共有8种：1:(2 × (3 + 10)) - 2 2:2 × (3 + 10) - 2 3:(2 × (10 + 3)) - 2 4:2 × (10 + 3) - 2 5:(3 + 10) × 2 - 2 6:((3 + 10) × 2) - 2 7:(10 + 3) × 2 - 2 8:((10 + 3) × 2) - 2