2016 AMC 8 Problems/Problem 17
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Problem
An ATM password at Fred's Bank is composed of four digits from to
, with repeated digits allowable. If no password may begin with the sequence
then how many passwords are possible?
Solutions
Solution 1
For the first three digits, there are combinations since
is not allowed. For the final digit, any of the
numbers are allowed.
Solution 2
Counting the prohibited cases, we find that there are 10 of them. This is because we start with 9,1,1 and we can have any of the 10 digits for the last digit. So our answer is
Video Solution
~savannahsolver
See Also
2016 AMC 8 (Problems • Answer Key • Resources) | ||
Preceded by Problem 16 |
Followed by Problem 18 | |
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All AJHSME/AMC 8 Problems and Solutions |
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