Number theoryDifficulty 2.0JuniorFind the answerUnited Kingdom
We will call a two-digit number power-less if neither of its digits can be written as an integer to a power greater than 1. For example, 53 is power-less, but 54 is not power-less since 4=22. Which of the following is a common divisor of the smallest and the largest power-less numbers?
(A) 3 (B) 5 (C) 7 (D) 11 (E) 13
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