The document discusses finding the greatest common factor (GCF) of numbers to help reduce fractions. It defines the GCF as the largest factor that is common to both numbers. It provides examples of finding the GCF using factor trees and lists. It notes that if both numbers are prime, their GCF is 1.

1. FRACTIONS Greatest Common Factor

2. Using What You Know . . . GREATEST COMMON FACTOR Helps Reduce fractions LEAST COMMON MULTIPLE Helps find Common Denominators

3. Using What You Learned . . . What’s the GCF ?? What factors do they share? Which of those factors is the largest? GREATEST COMMON FACTOR Helps reduce fractions = ?

4. Using What You Learned . . . What’s the GCF ?? You can list the factors You can make factor trees G REATEST C OMMON F ACTOR Helps reduce fractions = ?

5. Using What You Learned . . . What’s the GCF ?? Factor Tree 6 9 2 3 3 3 Circle the # when it is prime Line up the factors 6: 2 3 9: 3 3 GCF = 3 G REATEST C OMMON F ACTOR Helps reduce fractions = ?

6. Greatest Common Factor 5 20 THINK . . . G reatest . . . The biggest possible C ommon . . . They both have it F actor . . . A factor of both numbers

7. Greatest Common Factor HINT The GCF will ALWAYS be EQUAL to Or SMALLER than the smallest of the two (or three numbers)

8. Greatest Common Factor 3 and 7 5 and 7 11 and 13 All of these numbers are PRIME . IF both numbers are PRIME, the GCF will be 1.

9. Greatest Common Factor 3 and 7 5 and 7 11 and 13 All of these numbers are PRIME . IF both numbers are PRIME, the GCF will be 1. 1 1 1

10. Give It A Try – What’s the GCF ? 3 and 5 12 and 20 5, 3, and 7 3 and 9 4 and 12 6 and 12 10 and 25 14 and 24 6 and 9 15 and 100 1 4 1 3 4 6 5 2 3 5