Units digit — AMC & AIME Problems

Practice every real AMC 8, AMC 10, AMC 12, and AIME problem that uses Units digit — 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).

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AMC 8

1986 AMC 8 Problem 8 1990 AMC 8 Problem 4 1994 AMC 8 Problem 6 1996 AMC 8 Problem 15 1997 AMC 8 Problem 25 1999 AMC 8 Problem 24 2000 AMC 8 Problem 14 2012 AMC 8 Problem 12 2022 AMC 8 Problem 17 2024 AMC 8 Problem 1

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 factorizationquadratic residuesum of factorstrailing zerostriangular number