Answer to the Problem of the Week

for the week of February 14, 2000

Solve the following problem between Monday and Friday. Then click on the icon below to e-mail your solution along with your name, city, and state.

The Book Problem
It takes 852 digits to number the pages of a book consecutively. How many pages are there?

How many times is the digit 7 used?


Solution:

There are 320 pages in the book, and the digit 7 was used 62 times.

Pages Digits
1 - 9 9 digits
10 - 99 180 digits
100 - 320 663 digits
320 pages 852 digits
           
Pages Number of 7's
1 - 100 20 sevens
101 - 200 20 sevens
201 - 300 20 sevens
301 - 320 2 sevens


Correctly solved by:

1. Liz Cotter Oak Hill, VA
2. Tom Marino Winchester, VA
3. Richard Mocarski Winchester, VA
4. Chris Moats Winchester, VA
5. Bob Hearn Winchester, VA