Greatest Common Factor

Greatest Common Factor

Introduction Day

What to expect

• Bite-size lesson on GCF

• Examples from Ms. Rohan

• Questions for you

• Accuracy counts; can improve :)

Poll

What do you think "GCF" stands for?

(Just a poll; cannot count against you)

• Greatest Common Multiple

• Least Common Denominator

• Greatest Common Factor

• Least Common Multiple

What are factors?

Factors = evenly "go into" the original number

Factors Example

Your Turn!

You will need to pick all the factors of 16.

Do this by listing out all pairs of numbers that

multiply together to equal 16.

Fill in the Blanks

LIST ALL the factors of 8 from least to greatest.

1, 2, 4, 8

Fill in the Blanks

LIST ALL the factors of 18 from least to greatest.

1, 2, 3, 6, 9, 18

Fill in the Blanks

LIST all of the factors of 12 from least to greatest.

1, 2, 3, 4, 6, 12

Fill in the Blanks

LIST all of the factors of 16 from least to greatest (don't list repeats)

1, 2, 4, 8, 16

How to find

GREATEST COMMON FACTOR

Greatest Common Factor

You're about to see a 1 minute Youtube video

You can use headphones or just watch :)

It is completely possible to understand without hearing.

Greatest Common Factor

1. List the factors of each

2. Find the greatest one they have in common

Your Turn!

You'll have three problems to find the Greatest Common Factor (GCF).

Make sure you choose the greatest common factor...

not just any common factor!

Multiple Choice

Select the GCF of 12 and 16.

• 2

• 4

• 6

• 8

GCF of 12 and 16 is 4.

12's factors are: 1, 2, 3 ,4, 6, 12

16's factors are: 1, 2, 4, 8, 16

The greatest factor they have in common is 4!

Multiple Choice

Select the GCF of 8 and 16.

• 2

• 4

• 6

• 8

GCF of 8 and 16 is 8.

8's factors are: 1, 2, 4, 8

16's factors are: 1, 2, 4, 8, 16

The greatest factor they have in common is 8!

The next one is a little sneaky!

But still find the same way:

1. List all the factors of each number

2. Find the greatest one in common

Multiple Choice

Select the GCF of 5 and 6.

• 1

• 2

• 5

• 6

GCF of 5 and 6 is just 1.

5's factors are: 1, 5

6's factors are: 1, 2, 3, 6

The greatest factor they have in common is just 1.

*Some people just say there is no significant GCF, when it's just 1*

Woohoo!

You are nailing it! Keep it up!

We are going to increase the challenge a bit!

Greatest Common Factor with variables

We'll need to know how to find GCF of variables, too!

GCF with variables/exponents

• The greatest amount/exponent that each variable has in common (without going over!)

• Let's see an example...

Example 1

Example 2

Your Turn!

You'll find the GCF of between variable terms

Multiple Choice

What is the GCF of

 $x^4\ and\ x^9$  ?

•  $x^1$  

•  $x^4$  

•  $x^9$  

• none

Multiple Choice

What is the GCF of

 $x^6\ and\ x^9$  ?

•  $x^1$  

•  $x^3$  

•  $x^6$  

•  $x^9$  

Multiple Choice

What is the GCF of

 $x^{ }\ and\ x^3$  ?

•  $x^{ }$  

•  $x^3$  

•  $x^4$  

• none

Answer Explained: x

Great job!

Thank you for participating!

Be sure to try again to improve your score

for daily grade credit and to improve your understanding.