Pg 151
Find the GCF for each set of numbers.
1. 12,21
2. 30,45
3. 8, 13
4. 18, 72
5. 27, 42, 48
6. Number Sense The GCF of 6 and 24 is 6. Find two other pairs of numbers in which the first number
in each pair is the GCF.
Find the GCF for each set of numbers.
7. 14, 35
8. 32, 80
9. 50,75
10. 25,90
11. 15,36
12. 20, 25
13. 11, 15
14. 100, 200
15. 99, 121
16. 12, 49
17. 9, 18, 24
18. 13, 23
19. 54, 117
20. 20, 32, 44
21. 45, 36, 72
22. Number Sense Name two numbers for which the GCF is 1.
23. Chris wants to buy storage boxes that are all the same height and can be stacked on 24 inch or 30 inch
shelves with no spare space above or below. What is the tallest box that
will work?
24. Explain how you use prime factorization to find the GCF of 45 and 75.
The Venn diagram shows the common factors and the GCF of 30 and 42.
25. Tell what each shaded region show?
26. Use a Venn diagram to show common factors of 48 and 72. What is
the GCF?
Pg 153
Find the LCM of each set of numbers.
1. 4, 6
2. 3, 13
3. 15, 30
4. 6, 27
5. 5, 9, 15
6. Number Sense Find the LCM of 5 and 7, the LCM of 4 and 9, and the LCM of 3 and 10. What is special
about these LCMs?
Find the LCM of each set of numbers.
7. 6, 14
8. 3, 7
9. 10, 12
10. 18, 72
11. 20, 25
12. 6, 12, 30
13. 5, 12
14. 4, 22
15. 5, 6, 15
16. 8, 16, 24
17. 20, 30
18. 14, 21
19.Number Sense Find the LCM pg 5 and 10, the LCM of 4 and 12, and the LCM of 3 and 15. What is
special about these LCMs?
20. Mr. Peterson plays golf only on Saturday. He jogs every fourth day. If Mr. Peterson plays golf and jogs
on Saturday, how many days will it be before he golfs and jogs again on the same day?
21. Short films are shown continuously at the state fair. If the three films start together at 9:00am, what
time will it be when they all start at the same time again?
22. If one number is the multiple of another, what is the GCF? What is the LCM? (Hint: Test different pairs
such as 5 and 20 or 8 and 16)