Greatest Common Factor - Lesson 2 Revised

Greatest Common Factor - Lesson 2

Video Link - An Introduction

https://www.youtube.com/watch?v=crWLFqOQtBA

Greatest Common Factor

What is GCF (Greatest Common Factor)?

We find the Greatest Common Factor by COMPARING the common factors

Lets do an example

• What is the Greatest Common Factor of 20 and 8?

• We know how to find factors!!!

  Step 1: List the factors

  factors of 20: 1, 2, 4, 5, 10, 20

  factors of 8: 1, 2, 4, 8

  Step 2: Circle the common factors

  factors of 20: 1, 2, 4, 5, 10, 20

  factors of 8: 1, 2, 4, 8

• The Greatest Common Factor(GCF) is 4! Four is the biggest number they have in common.

Multiple Choice

What is the Great Common Factor of 8 and 24?

• 1

• 8

• 24

• 16

Answer: What is the Greatest Common Factor of 8 and 24?

• Factors of 8: 1, 2, 4, 8

• Factors of 24: 1, 2, 3, 4, 6, 8, 12, 24

• The highest number they have in common

  Greatest Common Factor: 8

Multiple Choice

What is the Greatest Common Factor of 15 and 36?

• 8

• 3

• 6

• 4

Answer: What is the Greatest Common Factor of 15 and 36?

• Factors of 15: 1, 3, 5, 15

• Factors of 36: 1, 2, 3, 4, 6, 9, 12, 18, 36

• GCF: 3

• Always write it out!

Multiple Choice

What is the Greatest Common Factor of 16 and 18?

• 6

• 4

• 2

• 8

What is the Greatest Common Factor of 16 and 18?

• 16: 1, 2, 4, 8, 16

• 18: 1, 2, 3, 6, 9, 18

• GCF: 2

Multiple Choice

What is the GCF of 12 and 28?

• 3

• 2

• 6

• 4

What is the GCF of 12 and 28?

• 12: 1, 2, 3, 4, 6, 12

• 28: 1, 2, 4, 7, 14, 28

• GCF: 4

Multiple Choice

GCF of 15 and 35?

• 15

• 3

• 7

• 5

GCF of 15 and 35?

• 15: 1, 3, 5, 15

• 35: 1, 5, 7, 35

• GCF: 5

Multiple Choice

Lets try it with three numbers!

What is the GCF of 8, 12, and 20?

• 2

• 6

• 8

• 4

What is the GCF of 8, 12, and 20?

8: 1, 2, 4, 8

12: 1, 2, 3, 4, 6, 12

20: 1, 2, 4, 5, 10, 20

GCF: 4

Lets try a word problem!

Linda has 20 forks and 16 knives to place in a silverware holders at the fast food restaurant where she works. She wants to distribute them equally with no forks or knives left over. What is the greatest number of silverware holders Linda can stock?

Factors of 20: 1, 2, 4, 5, 10, 20

Factors of 16: 1, 2, 4, 8, 16

The greatest number of silverware holder Linda can stock is 4

Multiple Choice

Stanley is putting together first-aid kits. He has 20 large bandages and 15 small bandages, and he wants each kits to be identical, with no bandages left over. What is the greatest number of first-aid kits Stanley could put together?

• GCF: 4

• GCF: 5

• GCF: 6

• GCF: 7

Answer

Stanley is putting together first-aid kits. He has 20 large bandages and 15 small bandages, and he wants each kits to be identical, with no bandages left over. What is the greatest number of first-aid kits Stanley could put together?

Factor of 20: 1, 2, 4, 5, 10, 20

Factor of 15: 1, 3, 5, 15

The greatest number of first-aid kits Stanley can put together is 5.

Multiple Choice

The Lin Corporation would like to donate 4 computer and 6 printers to local schools. The corporation would like to make sure that each school receives the same set of computers and printers, with none left over. What is the greatest number of schools that the Lin Corporation can donate to?

• 2

• 6

• 4

• 1

Answer

The Lin Corporation would like to donate 4 computer and 6 printers to local schools. The corporation would like to make sure that each school receives the same set of computers and printers, with none left over. What is the greatest number of schools that the Lin Corporation can donate to?

4: 1, 2, 4

6: 1, 2, 3, 6

The greatest number of schools that the Lin Corporation can donate to is 2.

Great Job!