Number theoryDifficulty 1.0JuniorFind the answerUnited Kingdom
How many of the following take integer values? 11, 1+111, 1+1+1111, 1+1+1+11111, 1+1+1+1+111111
(A) 0 (B) 1 (C) 2 (D) 3 (E) 4
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