Number theoryDifficulty 2.0JuniorFind the answerUnited Kingdom
The houses on the south side of Crazy Street are numbered in increasing order starting at 1 and using consecutive odd numbers, except that odd numbers that contain the digit 3 are missed out. What is the number of the 20th house on the south side of Crazy Street?
(A) 41 (B) 49 (C) 51 (D) 59 (E) 61
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