1: (9 × (7 + 1)) ÷ 3
2: 9 × (7 + 1) ÷ 3
3: 9 × ((7 + 1) ÷ 3)
4: (9 × (1 + 7)) ÷ 3
5: 9 × (1 + 7) ÷ 3
6: 9 × ((1 + 7) ÷ 3)
7: 9 ÷ 3 ×(7 + 1)
8: (9 ÷ 3) × (7 + 1)
9: 9 ÷ (3 ÷ (7 + 1))
10: 9 ÷ 3 ×(1 + 7)
11: (9 ÷ 3) × (1 + 7)
12: 9 ÷ (3 ÷ (1 + 7))
13: (7 + 1) × 9 ÷ 3
14: ((7 + 1) × 9) ÷ 3
15: (7 + 1) × (9 ÷ 3)
16: (7 + 1) ÷ 3 × 9
17: ((7 + 1) ÷ 3) × 9
18: (7 + 1) ÷ (3 ÷ 9)
19: (1 + 7) × 9 ÷ 3
20: ((1 + 7) × 9) ÷ 3
21: (1 + 7) × (9 ÷ 3)
22: (1 + 7) ÷ 3 × 9
23: ((1 + 7) ÷ 3) × 9
24: (1 + 7) ÷ (3 ÷ 9)
第一个算不出的
给你个网址吧
http://www.dffy.com/tool/24.htm
