GCF is the largest factor two numbers share. LCM is the smallest multiple both reach. GCF of 12 and 18 is 6. LCM is 36. Desmos can do this with functions, in lcm, gcd, and mod.
Factor, then pick
List prime factors. Shared primes with the smaller exponents are the GCF. All primes with the larger exponents are the LCM. Integers as a set are in integers on ACT Math.
Square roots are a different leftover skill, in square roots. The short list is in ACT Math formulas.
The bottom line
Shared factors: GCF. Shared multiples: LCM. Do not swap them.
Start practicing
Start with a free diagnostic, then drill your weak spots with 15-question quizzes and track how you're doing across Reading, English, and Math. Compare plans whenever you're ready to go further.
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