1. Lesson 4-5 Prime Factorization Page 160

2. Vocabulary words  Composite number-has more than 2 factors.  Example: 24: 1x 24, 2 x 12, 3x8, 4x6  Prime number- has only two factors, one and itself.  Example: 7: 1x7; 11: 1 x 11

3. Prime factorization  To write the prime factorization of a composite number you write the number as the product of prime factors.  A factor tree helps you find the prime factors of a number.

4. Using a factor tree  Use a factor tree to write the prime factorization of 60.  60  2 30  2 15  3 5  60 = 2x2x3x5 or 2^2x3x5

5. Make a factor tree to write the prime factorization of 28.  28  4 7  2 2  So 2 x 2 x 7 or 2^2 x7

6. Greatest common factor (GCF)  The GCF is the greatest number that is a factor of 2 or more numbers.  Example: Find the GCF or 24 and 36  Step 1: write the prime factorization of each number.  24 = 2x2x2x3  36=2x2x3x3  Step 2: Find the product of the common prime factors. 2x2x3=12

7. Find the GCF of the following  16 and 24  Answer: 8  15 and 25  Answer: 5  9 and 45  Answer: 9  28 and 42  Answer: 14

8. Today you learned  How to determine if a number is prime or composite.  How to use a factor tree  How to find the GCF of a number.

9. Assignment:  WORKSHEET PRACTICE 4-5  SHOW WORK