Maths Olympiad Prep

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Number theory Difficulty 2.0 Junior Find the answer United 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) 4141 (B) 4949 (C) 5151 (D) 5959 (E) 6161

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