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 of these problems are used with official legal permission of the Mathematical Association of America (MAA).
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
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
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