14 Labeled as $1,2, \cdots, 100$, there are some matches in the matchboxes. If each question allows asking about the parity of the sum of matches in any 15 boxes, then to determine the parity of the number of matches in box 1, at least how many questions are needed?
14. At least 3 questions are needed.

First, prove that "3 questions are sufficient." For example:
The first question is: $a_{1}, a_{2}, \cdots, a_{15}$;
The second question is: $a_{1}, a_{2}, \cdots, a_{8}, a_{16}, a_{17}, \cdots, a_{22}$;
The third question is: $a_{1}, a_{9}, a_{10}, \cdots, a_{22}$.
Here, $a_{i}$ represents the number of matches in the $i$-th box. In this way, the parity (odd or even) of the sum of the three answers is the same as the parity of $a_{1}$ (the other boxes each appear exactly twice in the three questions). Therefore, after 3 questions, the parity of $a_{1}$ can be determined.

Next, prove that "at least 3 questions are needed." If there are only two questions, and $a_{1}$ appears in both questions, then there must be $a_{i}$ and $a_{j}$ in the two questions such that $a_{i}$ appears only in the first question, and $a_{j}$ appears only in the second question. By changing the parity of $a_{1}$, $a_{i}$, and $a_{j}$ simultaneously, the answers to each question remain the same, thus the parity of $a_{1}$ cannot be determined. If $a_{1}$ does not appear in both questions, when $a_{1}$ does not appear at all, change the parity of $a_{1}$; when $a_{1}$ appears only once, change the parity of $a_{1}$ and $a_{i}$ (where $a_{i}$ is a box that appears with $a_{1}$ in the question), then the answers to the two questions remain the same, and the parity of $a_{1}$ cannot be determined.

In summary, at least 3 questions are needed.