6. (5 points) A fairy tale book has two volumes, upper and lower, and a total of 999 digits were used. The upper volume has 9 more pages than the lower volume. The upper volume has a total of pages.
【Answer】Solution:
The lower volume has 9 more pages, which means 9 more digits, i.e., $9 \times 3=27$ more digits
$$
\begin{array}{l}
(999-27) \div 2=972 \div 2=486 \text { (digits) } \\
486-9-180=297 \text { (digits) } \\
297 \div 3=99 \\
99+9+90+9=207 \text { (pages) }
\end{array}
$$

Therefore, the answer is 207