Library / /249 of 472

, 1998

Combinatorics Difficulty 2.0 Junior Find the answer Canada

Using only digits 1, 2, 3, 4, and 5, a sequence is created as follows: one 1, two 2's, three 3's, four 4's, five 5's, six 1's, seven 2's, and so on. The sequence appears as: $1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5, 1, 1, 1, 1, 1, 1, 2, 2, ...$ . The 100th digit in the sequence is

(A) $1$ (B) $2$ (C) $3$ (D) $4$ (E) $5$

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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.