Difference between revisions of "Mock AIME 3 Pre 2005 Problems/Problem 2"
(should I edit the question? N is less than 1000.) |
m (Mock AIME 3 Pre 2005/Problem 2 moved to Mock AIME 3 Pre 2005 Problems/Problem 2: same reason as before) |
(No difference)
| |
Revision as of 18:49, 19 June 2008
Problem
Let 
denote the number of 
digit positive integers have the property that their digits are in increasing order. Determine the remainder obtained when is divided by 
. (Repeated digits are allowed.)
Solution
Since the digits must be in increasing order, they must all be non-zero. We choose 7 digits out of 9, and when we do, they have only one order, so we choose them regardless of order, or 
.
