《怎样解题：数学竞赛攻关宝典（第3版）》第 37 页：

• a: 售票员 A 的年龄（the age of the wizard）
• b: 公交车的号码（the number of the bus）
• c: 孩子的数量（the number of the children）

1. 给定 a, b, c，售票员 B 无法推断出各个孩子的年龄
2. 给定 b，售票员 B 可以推断出 a 的（唯一的）值

• a = 1, c = 5, (1, 1, 1, 1, 1)
• a = 2, c = 4, (1, 1, 1, 2)
• a = 3, c = 3, (1, 1, 3)
• a = 4, c = 3, (1, 2, 2)
• a = 4, c = 2, (1, 4)
• a = 5, c = 1, (5)

• a = 96, c = 3, (1, 8, 12)
• a = 96, c = 3, (2, 3, 16)

• a = 240, c = 3, (4, 5, 12)
• a = 240, c = 3, (3, 8, 10)

• a = 96, c = 4, (1, 1, 8, 12)
• a = 96, c = 4, (1, 2, 3, 16)
• a = 240, c = 4, (1, 4, 5, 12)
• a = 240, c = 4, (1, 3, 8, 10)

• a = 48, c = 4, (1, 3, 4, 4)
• a = 48, c = 4, (2, 2, 2, 6)

• a = 1, c = 12, (1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)
• a = 2, c = 11, (1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2)
• a = 4, c = 10, (1, 1, 1, 1, 1, 1, 1, 1, 2, 2)
• a = 6, c = 9, (1, 1, 1, 1, 1, 1, 1, 2, 3)
• a = 11, c = 2, (1, 11)
• a = 12, c = 1, (12)
• ……

• a = 36, c = 3, (1, 6, 6)
• a = 36, c = 3, (2, 2, 9)
• a = 48, c = 5, (1, 1, 3, 4, 4)
• a = 48, c = 5, (1, 2, 2, 2, 6)