12. Xiao Qian, Xiao Lu, and Xiao Dai are guessing a natural number between 1-99, and the result is:

Xiao Qian says: “It is a perfect square, and it is less than 5.”
Xiao Lu says: “It is less than 7, and it is a two-digit number.”
Xiao Dai says: “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, $4=2$ squared, 81=9 squared, so we call $4$ and $9$ perfect squares).
【Answer】9
Analysis: (Method one) Through experimentation, the following situations meet the requirements:
\begin{tabular}{|l|l|l|l|}
\hline & Xiao Qian & Xiao Lu & Xiao Dai \\
\hline First half & True & False & True \\
\hline Second half & False & True \\
\hline
\end{tabular}

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, so it cannot be entirely true. Xiao Qian and Xiao Dai's first halves are either both true or both false, and they can only be both true. Therefore, Xiao Lu is entirely false, and at the same time, Xiao Qian is half true and half false. This is a single-digit perfect square greater than or equal to 5, which can only be 9.