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, 2011

Combinatorics Difficulty 2.0 Junior Find the answer Canada

How many positive integers less than 400 can be created using only the digits 1, 2 or 3, with repetition of digits allowed?

(A) $30$ (B) $33$ (C) $36$ (D) $39$ (E) $42$

Want a route through all this instead of an archive? The track puts 2,604 problems in a working order, from Junior Challenge level to the IMO shortlist.

Source: CEMC, University of Waterloo, licensed CC-BY-NC-4.0. Statement reproduced verbatim; metadata (topic, difficulty) added by this project. Solutions are the publisher's, linked not copied.