Intermediate Page Numbers

[noreply]

A total of 642 digits was used in numbering the pages of a book. How many pages did the book contain?

[JosePereira11]

Originally Posted by noreply

A total of 642 digits was used in numbering the pages of a book. How many pages did the book contain?

Hi noreply. First i must congratulate you by your activity in xp maths along with MAS1 in what concerns putting and resolving problems.

This one is easy but funny. =)
So, first we suppose that all the pages are numbered.
Then:
1-9 page its 9 digits
10-99 page its 180 digits (99-9=90 ; 90*2=180)

We stop here. We already have 9+180 digits = 189 . We need 642-189=453 ;
453/3 = 151

151+99=250

Result: 250 pages.

[jorgea]

250 pages. Thanks for creating this challenge question here at http://www.xpmath.com