16. The book has 568 pages. How many digits in total have been used for numbering from the first to the last page of the book?
16. There are 9 single-digit numbers, so 9 digits are needed for numbering single-digit pages. ..... 2 POINTS
There are 90 two-digit numbers, so $90 \cdot 2=180$ digits are needed for numbering two-digit pages. ..... 2 POINTS
There are $568-99=469$ three-digit numbers on the pages of the book, so $469 \cdot 3=1407$ digits are needed for their numbering. ..... $4 \text{POINTS}$
Thus, for numbering the book, $9+180+1407=1596$ digits are needed. ..... 2 POINTS
TOTAL 10 POINTS