1. GCF (Greatest Common Factor) Standard: check 0706.1.1 Created by Penelope Rogers

2. First lets review a common factor A common factor is when two or more numbers have the same numbers as factors. Example: Factors of 12 and 30 Factors of 12 are 1, 2, 3, 4, 6 and 12 Factors of 30 are 1, 2, 3, 5, 6, 10, 15 and 30 What are ALL the common factors?

3. Common Factors of 12 and 30 1, 2, 3, 6 These four numbers are all factors of both the numbers of 12 and 30. Therefore they are said to be the common factors.

4. GCF – Greatest Common Factor It is simply the largest of the common factors. The "Greatest Common Factor“ or GCF is the largest of the common factors (of two or more numbers).

5. Lets take the same example: What is the GCF of 12 and 30? Factors of 12 are 1, 2, 3, 4, 6 and 12 Factors of 30 are 1, 2, 3, 5, 6, 10, 15 and 30 ??think?? think?? think?? think??

6. The GCF of 12 AND 30 is…….. 6

7. 3 methods to find the GCF 1. Factors 2. Factor Trees 3. Upside Down Birthday Cake Does it matter which method YOU chose to use? You solve the GCF with the method that best fits you!

8. Method 1 – Factors (old school) Lets look at an example of GCF using the method of Factors. http://studyjams.scholastic.com/studyjams/jams /math/fractions/greatest-common-factor.htm http://studyjams.scholastic.com/studyjams/jams /math/fractions/greatest-common-factor.htm This is study jams on step by step under home.

9. Method 2 – Factor Trees Lets look at an example of GCF using the method of Factor Trees using the same problem. http://studyjams.scholastic.com/studyjams/ja ms/math/fractions/greatest-common- factor.htm http://studyjams.scholastic.com/studyjams/ja ms/math/fractions/greatest-common- factor.htm This is study jams under watch out.

10. Method 3 – Upside Down Birthday Cake Lets look at an example of GCF using the method of Upside Down Birthday Cake. http://www.youtube.com/watch?v=GD5jLpSs N00 http://www.youtube.com/watch?v=GD5jLpSs N00

11. Decisions and Practice Decide which method is BEST for YOU. Lets practice some homework problems using each method. Happy finding GCF. Have a great day and thanks for stopping by.