Difference between revisions of "2006 Alabama ARML TST Problems/Problem 11"
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[[Category:Intermediate Number Theory Problems]] | [[Category:Intermediate Number Theory Problems]] | ||
Revision as of 12:13, 29 September 2008
Problem
The integer 
has 1403 digits, and 1 is its first digit (farthest to the left). For how many integers 
does 
begin with the digit 1?
Solution
Now either starts with 1, or 
has one more digit than . From 
to 
, we have 1401 changes, so those must not begin with the digit 1. 
See also
| 2006 Alabama ARML TST (Problems) | ||
| Preceded by: Problem 10 |
Followed by: Problem 12 | |
| 1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 | ||
