Find what numbers share and what they need in common.
The Greatest Common Factor (GCF) is the largest factor shared by two or more numbers. The Least Common Multiple (LCM) is the smallest multiple shared by two or more numbers. Both are found using prime factorization or lists.
GCF of 12 and 18
LCM of 4 and 6
GCF is used to simplify fractions. LCM is used to find common denominators.
You have 24 apples and 36 oranges. You want to make identical gift bags using all the fruit. The GCF(24, 36) = 12. You can make 12 bags, each with 2 apples and 3 oranges.
Remember This!
Use prime factorization for efficiency: GCF = product of shared prime factors (lowest powers). LCM = product of all prime factors (highest powers).
What is the LCM of 8 and 12?