1. Finding the Greatest Common Factor
Grade 5

2. Lesson Objectives 6.B.1.c Identify the greatest common factor
3.A.1.a Use technology tools, including software and hardware, from a range of teacher-selected options to learn a new content or reinforce skills

3. Think Backwards… Find Factors Circle Common Factors
Group Greatest Factor

4. Step 1: Find the Factors 24 – 1,2,3,4,6,8,12,24
36 – 1,2,3,4,6,9,12,18,36

5. Step 2: Circle Common Factors
24 – 1,2,3,4,6,8,12,24
36 – 1,2,3,4,6,9,12,18,36

6. Step 3: Group the Greatest Factor
24 – 1,2,3,4,6,8,12,24
36 – 1,2,3,4,6,9,12,18,36

7. The Greatest Common Factor of 24 and 36 is…12

8. Now let’s try finding the GCF

9. Find the GCF of 12 and 24 Step 1: Find the factors 12 – 1,2,3,4,6,12
24 – 1,2,3,4,6,8,12,24

10. Find the GCF of 12 and 24 Step 2: Circle the common factors
12 – 1,2,3,4,6,12
24 – 1,2,3,4,6,8,12,24

11. Find the GCF of 12 and 24 Step 3: Group the greatest factor
12 – 1,2,3,4,6,12
24 – 1,2,3,4,6,8,12,24

12. The Greatest Common Factor of 12 and 24 is …

13. Your turn! Find the Greatest Common Factor of 16 and 20.
Remember…Find Factors, Circle Common, Group Greatest!

14. The Greatest Common Factor of 16 and 20 is…4

15. Are you ready?
Let's try some more!