12. Xiao Qian, Xiao Lu, and Xiao Dai are guessing a natural number between 1 and 99. The results:

Xiao Qian said: “It is a perfect square, and it is less than 5.”
Xiao Lu said: “It is less than 7, and it is a two-digit number.”
Xiao Dai said: “The first half of what Xiao Qian said is true, but the second half is false.”
If among these 3 people, 1 person is telling the truth in both statements, 1 person is lying in both statements, and 1 person is telling the truth in one statement and lying in the other. Then, what is this number? (Note: A perfect square is a number that can be expressed as the square of an integer, for example, $4=2^2$, $81=9^2$, so we call 4 and 9 perfect squares).
【Answer】9
Analysis: (Method one) Through experimentation, the following situations meet the requirements:
So this number is a perfect square greater than or equal to 7, and it is a single-digit number, hence it can only be 9.
(Method two) Xiao Lu's statement is self-contradictory and cannot be entirely correct. Xiao Qian and Xiao Dai's first half of the statements are either both true or both false, so they must both be true. Therefore, Xiao Lu's statements are all false, and at the same time, Xiao Qian's statements are one true and one false. This is a single-digit perfect square greater than or equal to 5, which can only be 9.