1. 5-1& 5-2 Prime Factors and Greatest Common Factors Vocab: Prime Numbers(5-1) A whole number with exactly 2 factors (1 and itself) ex 17: 1,17 1 is not Prime!! Composite Numbers(5-1) A whole number with more than 2 factors ex 8: 1,2,4,8 Prime Factorization: Write a composite number as a product of only primes. 18 = 2x3x3 Greatest Common factor: The largest factor 2 or more numbers share (will divide into both numbers evenly)

2. To find the GCF using lists of factors Write all the factors of the following numbers 20 : 24: 20:1, 2, 4, 5, 10, 20 24:1, 2, 3, 4, 6, 8, 12, 24 5 10 20 124124 3 6 8 24 12 Factors of 20 Factors of 24 The greatest common factor(GCF) is 4

3. Find the GCF of 6 and 12 6:1,2,3,6 12:1,2,3,4,6,12 1 2 3 4 6 12 The GCF is 6

4. Find GCF with Prime Factors Find the Prime factors of 45 and 36 36 = 6 x 6 = 2x3x2x3 ←all primes =2x2x3x3←rewrite in order 45 = 9 X 5 = 3x3x5←all primes (in order) So 36 = 2x2x3x3 45 = 3x3x5 3x 3 is on both lists so the GCF is 3x3 =9

5. Find the GCF of 30 a 2 and 18 a 3 b 30 a 2 = 2x3x5xaxa 18a 3 b = 2x3x3xaxaxaxb 2x3xaxa is on both lists so the GCF is 2x3xaxa=6a 2

6. Period 6 & 7 5-1/199/33-35,50,51 5-2/205-206/26-33,39-44,47 Periods 1, 3, & 8 5-2/205-206/9-19 o,39-44,46,47