24点题目：使用数字 2 9 9 12，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48个解（使用交换律变换后算一个解）,
难度系数是1星
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最简单入门24点题目
】。
| 序号 |
题目：2,9,9,12 |
| 1 |
((12 + 9) − 9) × 2 |
| 2 |
((12 × 2) + 9) − 9 |
| 3 |
((9 + 9) × 2) − 12 |
| 4 |
((12 × 2) − 9) + 9 |
| 5 |
(9 + (12 − 9)) × 2 |
| 6 |
(12 × 2) − (9 − 9) |
| 7 |
(12 + (9 − 9)) × 2 |
| 8 |
(12 × 2) + (9 − 9) |
| 9 |
(12 − (9 − 9)) × 2 |
| 10 |
12 × (2 − (9 − 9)) |
| 11 |
12 × (2 + (9 − 9)) |
| 12 |
12 × ((9 + 2) − 9) |
| 13 |
12 × (9 − (9 − 2)) |
| 14 |
((12 × 2) × 9) ÷ 9 |
| 15 |
((9 × 2) × 12) ÷ 9 |
| 16 |
((12 × 9) ÷ 9) × 2 |
| 17 |
((12 × 9) × 2) ÷ 9 |
| 18 |
(12 × 2) ÷ (9 ÷ 9) |
| 19 |
(12 × (9 ÷ 9)) × 2 |
| 20 |
(9 + (12 ÷ 2)) + 9 |
| 21 |
(12 ÷ (9 ÷ 9)) × 2 |
| 22 |
(12 × 2) × (9 ÷ 9) |
| 23 |
(9 + 9) + (12 ÷ 2) |
| 24 |
12 × (2 ÷ (9 ÷ 9)) |
| 25 |
12 × (2 × (9 ÷ 9)) |
| 26 |
12 × ((9 × 2) ÷ 9) |
| 27 |
(9 ÷ (9 ÷ 12)) × 2 |
| 28 |
(12 × 9) ÷ (9 ÷ 2) |
| 29 |
(9 × 2) × (12 ÷ 9) |
| 30 |
(9 × (12 ÷ 9)) × 2 |
| 31 |
(9 × 2) ÷ (9 ÷ 12) |
| 32 |
(12 × 9) × (2 ÷ 9) |
| 33 |
12 ÷ (9 ÷ (9 × 2)) |
| 34 |
9 × (2 ÷ (9 ÷ 12)) |
| 35 |
12 × (9 ÷ (9 ÷ 2)) |
| 36 |
9 ÷ ((9 ÷ 12) ÷ 2) |
| 37 |
12 ÷ ((9 ÷ 2) ÷ 9) |
| 38 |
2 ÷ ((9 ÷ 9) ÷ 12) |
| 39 |
9 × (12 × (2 ÷ 9)) |
| 40 |
9 ÷ ((9 ÷ 2) ÷ 12) |
| 41 |
2 ÷ ((9 ÷ 12) ÷ 9) |
| 42 |
12 ÷ ((9 ÷ 9) ÷ 2) |
| 43 |
9 × (2 × (12 ÷ 9)) |
| 44 |
12 × (9 × (2 ÷ 9)) |
| 45 |
9 × ((12 × 2) ÷ 9) |
| 46 |
9 × (12 ÷ (9 ÷ 2)) |
| 47 |
2 ÷ (9 ÷ (12 × 9)) |
| 48 |
9 ÷ (9 ÷ (12 × 2)) |