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number theory intermediate
Problem
Let be an infinite repeating decimal with the digits and repeating. When is written as a fraction in lowest terms, the denominator exceeds the numerator by
(A)
(B)
(C)
(D)
Solution
Multiplying by gives . Subtracting the first equation from the second gives , and all the other repeating parts cancel out. This gives . Subtracting the numerator from the denominator gives .
Final answer
D