6. (10 points) 44 guests were invited to a banquet, and there are 15 identical square tables in the venue, with each side able to seat 1 person. After appropriate "table merging" (combining several squares into a rectangular or square table), all guests can be seated with no empty seats. Therefore, the minimum number of tables in the venue is $\qquad$.

【Solution】Solution: $15 \times 4=60$ (units)
Reduced tables: $(60-44) \div 2$
$$
\begin{array}{l}
=16 \div 2 \\
=8 \text { (tables) }
\end{array}
$$

Remaining tables: $15-8=7$ (tables)
It can be illustrated as follows: (Not a unique answer) Answer: There will be at least 7 tables left in the venue. Therefore, the answer is: 7.