CEMC Fermat, 2005

Algebra Difficulty 1.0 Junior Find the answer Canada

The sum of the first 2005 terms of the sequence $1, 2, 3, 4, 1, 2, 3, 4, \ldots$ is

(A) $5011$ (B) $5110$ (C) $5020$ (D) $5010$ (E) $501$

We don't reproduce this publisher's solutions. Their own solution is here — work the problem first.

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.