Sum of factors — AMC & AIME Problems

Practice every real AMC 8, AMC 10, AMC 12, and AIME problem that uses sum of factors — 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

2007 AMC 8 Problem 10

AMC 10

2008 AMC 10A Problem 3 · 2013 AMC 10B Problem 24 · 2021 AMC 10B Spring Problem 12

More number theory concepts

Chicken McNugget TheoremChinese Remainder Theoremcontinued fractiondigitsDiophantine EquationdivisibilityEuler’s Totient Functionfactorfactor countingFermat’s Little Theoremgreatest common divisorleast common multipleLegendre’s Formulamodular arithmeticmodular exponentiationmultiplemultiplicative orderpalindromeparityperfect powerperfect squarepower of 2primeprime factorizationtrailing zerostriangular numberunits digit