Problem:
On a trip from the United States to Canada, Isabella took U.S. dollars. At the border she exchanged them all, receiving Canadian dollars for every U.S. dollars. After spending Canadian dollars, she had Canadian dollars left. What is the sum of the digits of ?
Answer Choices:
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B.
C.
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E.
Solution:
Isabella received Canadian dollars at the border and spent of them. Thus , from which it follows that , and the sum of the digits of is .
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions