# Finding the common factors and greatest common factors!

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Finding the common factors and greatest common factors!
Need chart paper

Guiding Question How can I find the common factors of a set of numbers? How can I find the Greatest Common Factor of a set of numbers?

Factors Remember, factors are all the numbers that can be multiplied to make a certain number. For example: 24 I start with ? When do I stop? What are the factors of 24?

“COMMON” What does it mean to have something “in common”?
If 2 is a factor of 24, and 2 is also a factor of 12, then 24 and 12 both have 2 as a factor. They have that ‘in common’. COMMON FACTORS!

Let’s find all the common factors for 12 and 24
First list the factors for each like this: 12: 24: Next, write out all the common factors:

Finding Common Factors of 12 and 18

Brain Pop! Here is a Brain Pop video all about factors, greatest common factor, and other things we have learned! Factoring

Your Turn With your partner, find all the common factors for 8 and 20
When you are finished, use chart paper and markers to explain what strategies you used, and how you found the common factors! Go to glass for next slide

GREATEST COMMON FACTOR (GCF)
Once you have found all the common factors, it’s very simple to find the Greatest common factor. Greatest = Largest: 12: 24: Common Factors: What is the Largest (Greatest) factor that they share? This is the Greatest common factor! GLASS MODE

Your Turn! Find the Greatest Common Factor for: 12, 30 16, 32
12, , 32 21,42 27, 45 Be prepared to share your strategy with the class!

Which list contains all the common factors for 6 and 12?
1, 2, 3 2, 3, 6 1, 2, 3, 6 1, 2, 3, 4, 6, 12

Partner Work Product Factors Prime or Composite activity with dice.

Let’s review our Guiding Questions
How can you find the common factors of a set of numbers? How can you find the Greatest Common Factor of a set of numbers? Jot down your thinking in your journal.

Portfolio Use chart paper. With your group, demonstrate what you know about arrays factors, prime and composite numbers. Use words, pictures, and diagrams. Make sure you use the following vocabulary words in your writing: factor, array, product, dimension, equation, multiplication combination