Factor counting — AMC & AIME Problems
Practice every real AMC 8, AMC 10, AMC 12, and AIME problem that uses Factor counting — a number theory concept — each with a professionally curated solution, many with a video solution too, from LIVE by Po-Shen Loh. Browse all concepts or the full past-contest archive.
All problems are used with official legal permission of the Mathematical Association of America (MAA).
Filter by difficulty
These problems’ difficulty ratings come from real solve attempts on our platform. Tap a band or a contest to filter the list below, and tap a selected band again to include all difficulties. See the full difficulty guide.
AMC 8
1997 AMC 8 Problem 11 • 2015 AMC 8 Problem 22 • 2018 AMC 8 Problem 18 • 2020 AMC 8 Problem 17 • 2025 AMC 8 Problem 22
AMC 10
2005 AMC 10A Problem 15 • 2009 AMC 10A Problem 19 • 2010 AMC 10B Problem 8 • 2012 AMC 10B Problem 10 • 2013 AMC 10A Problem 19 • 2016 AMC 10A Problem 22 • 2016 AMC 10B Problem 18 • 2017 AMC 10B Problem 20 • 2018 AMC 10B Problem 19 • 2019 AMC 10B Problem 19 • 2020 AMC 10A Problem 15 • 2020 AMC 10A Problem 22 • 2021 AMC 10A Fall Problem 23 • 2021 AMC 10B Fall Problem 6 • 2023 AMC 10A Problem 14 • 2024 AMC 10B Problem 8
AMC 12
1964 AMC 12 Problem 28 • 1974 AMC 12 Problem 26 • 2000 AMC 12 Problem 7 • 2003 AMC 12A Problem 8 • 2003 AMC 12A Problem 23 • 2005 AMC 12B Problem 21 • 2008 AMC 12B Problem 23 • 2010 AMC 12B Problem 3 • 2013 AMC 12B Problem 25 • 2016 AMC 12A Problem 18 • 2016 AMC 12B Problem 16 • 2017 AMC 12B Problem 16 • 2018 AMC 12B Problem 14 • 2021 AMC 12A Spring Problem 25 • 2021 AMC 12A Fall Problem 20 • 2022 AMC 12A Problem 25
AIME
1986 AIME Problem 8 • 1987 AIME Problem 3 • 1988 AIME Problem 5 • 1990 AIME Problem 5 • 1995 AIME Problem 6 • 1995 AIME Problem 11 • 1996 AIME Problem 8 • 2000 AIME II Problem 2 • 2000 AIME II Problem 4 • 2004 AIME II Problem 8 • 2005 AIME I Problem 2 • 2005 AIME I Problem 3 • 2005 AIME I Problem 12 • 2005 AIME II Problem 4 • 2006 AIME II Problem 13 • 2010 AIME I Problem 1 • 2011 AIME I Problem 7 • 2016 AIME II Problem 11 • 2019 AIME I Problem 9 • 2019 AIME II Problem 3 • 2019 AIME II Problem 9 • 2020 AIME I Problem 12 • 2023 AIME II Problem 10 • 2026 AIME I Problem 6 • 2026 AIME II Problem 9