Mock AIME 2 Pre 2005 Problems/Problem 4
Problem
Let . Given that has digits, how many elements of begin with the digit ?
Solution
Note that has the same number of digits as if and only if has a leading digit . Therefore, there are numbers with leading digit among the set However, also starts with , so the answer is .
-MP8148
See also
Mock AIME 2 Pre 2005 (Problems, Source) | ||
Preceded by Problem 3 |
Followed by Problem 5 | |
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