Official material: complete proof · OBMEP solutions · collection of the year. The resolutions below follow the numbering of the official notebook. Open the test to follow the statements, alternatives and diagrams; The explanations here are copyright. Attempt each question before checking the answer. Template Questions Answers 1–5 B · B · E · C · D 6–10 A · E · A · B · E 11–15 E · B · D · C · D 16–20 D · E · C · B · D Question 1 — Overlap And it was glued last. A is below it and above B; B covers C and D. Therefore the first two are C and D, the third is B, the fourth A and the fifth E. Alternative B.
Official material: complete proof · OBMEP solutions · collection of the year. The resolutions below follow the numbering of the official notebook. Open the test to follow the statements, alternatives and diagrams; The explanations here are copyright. Attempt each question before checking the answer. Question 1 — Cards and multiples a) One possibility is $6,2,4,8,1,9,3$. Checking the pairs, we have divisibility in all of them: 6 by 2, 4 by 2, 8 by 4, 8 by 1, 9 by 1 and 9 by 3.