24点题目：使用数字 1 2 9 13，利用加减乘除、括号算出24。数字顺序可以任意调换，下面列出所有可行算式。
本题共有30个解（使用交换律变换后算一个解）,
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中等偏易24点题目
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| 序号 |
题目：1,2,9,13 |
| 1 |
((13 × 1) + 2) + 9 |
| 2 |
((13 × 1) + 9) + 2 |
| 3 |
((13 + 9) + 2) × 1 |
| 4 |
((13 + 2) × 1) + 9 |
| 5 |
((13 + 9) × 1) + 2 |
| 6 |
((13 + 2) + 9) × 1 |
| 7 |
(13 + (9 × 1)) + 2 |
| 8 |
(13 × 1) + (9 + 2) |
| 9 |
(13 + 9) + (2 × 1) |
| 10 |
(13 + (2 × 1)) + 9 |
| 11 |
(13 + (9 + 2)) × 1 |
| 12 |
(13 + 2) + (9 × 1) |
| 13 |
13 + ((9 × 1) + 2) |
| 14 |
13 + ((9 + 2) × 1) |
| 15 |
13 + (9 + (2 × 1)) |
| 16 |
((13 + 9) + 2) ÷ 1 |
| 17 |
((13 + 9) ÷ 1) + 2 |
| 18 |
((13 ÷ 1) + 9) + 2 |
| 19 |
((13 + 2) + 9) ÷ 1 |
| 20 |
((13 + 2) ÷ 1) + 9 |
| 21 |
((13 ÷ 1) + 2) + 9 |
| 22 |
(13 + (9 + 2)) ÷ 1 |
| 23 |
(13 + (2 ÷ 1)) + 9 |
| 24 |
(13 ÷ 1) + (9 + 2) |
| 25 |
(13 + 2) + (9 ÷ 1) |
| 26 |
(13 + (9 ÷ 1)) + 2 |
| 27 |
(13 + 9) + (2 ÷ 1) |
| 28 |
13 + (9 + (2 ÷ 1)) |
| 29 |
13 + ((9 + 2) ÷ 1) |
| 30 |
13 + ((9 ÷ 1) + 2) |