1. Find the greatest common factor of two or more numbers
Chapter 5 Lesson 2
Objective:
Find the greatest common factor of two or more numbers

2. Vocabulary Greatest Common Factor
Factors that are common to two or more numbers.

3. There are 2 ways to find the GCF!
First way is to list the factors
Second way is to use Prime Factorization

4. Lets start by listing the factors

5. Find the GCF of 20 and 24. 20
1,2,4,5,10,20 24
1,2,3,4,6,8,12,24
GCF is 4

6. Find the GCF of each pair of numbers.
8 and 10
8: 1,2,4,8
10: 1,2,5,10
GCF is 2
6 and 12
6: 1,2,3,6
12: 1,2,3,4,6,12
GCF is 6

7. Find the GCF of each pair of numbers.
10 and 17
10: 1,2,5,10
17: 1,17
GCF is 1

8. Now lets try using prime factorization

9. Find the GCF if each set of numbers using prime factorization.
18 and 48 18 9
3 3
2 x 3 x 3 48 24
2 12
3 4
2 2
2 x 2 x 2 x 2 x 3
2 x 3 = 6
GCF is 6

10. Find the GCF of 12 and 78 using prime factorization.
You try a few
Find the GCF of 12 and 78 using prime factorization.
GCF is 6

11. Find the GCF of 32 and 48 using prime factorization.
Try this one
Find the GCF of 32 and 48 using prime factorization.
GCF is 16

12. Which way do you like to find the GCF?
QUESTION???
Which way do you like to find the GCF?
Why?

13. Try some on your own. Page 205 numbers 9-29 odd Homework
Page 205 numbers even