Name
LESSON
Date
Class
Practice C
3-1 Prime Factorization
Tell whether each number is prime or composite.
1. 91
2. 117
3. 109
4. 73
Write the prime factorization of each number.
5. 84
6. 343
7. 135
8. 180
Use a step diagram to find the prime factorization.
9. 290
10. 900
11. 575
12. 90
13. 220
14. 350
15. 495
16. 480
17. 2,000
18. 1,040
19. 1,650
20. 3,000
21. The prime factorization of a number is 22 • 35. What is
the number?
22. You can factor 150 as 15 • 10. List four other ways can you
factor 150.
23. A number x is a prime factor of 65 and 104. What is the number?
Write the composite number for each prime factorization.
24. 25 • 52
25. 33 • 5 • 11
26. 43 • 7 • 13
27. 28 • 35
28. The prime factors of a number are all the prime numbers
between 20 and 30. No factor is repeated. What is the number?
Copyright © by Holt, Rinehart and Winston.
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7
Holt Mathematics
Practice B
3-1 Prime Factorization
Practice A
3-1 Prime Factorization
LESSON
LESSON
Tell whether each number is prime or composite.
1. 25
2. 16
Composite
Tell whether each number is prime or composite.
3. 21
Composite
4. 29
Composite
1. 33
Prime
Composite
5. What is the prime factorization of 24?
A 23 • 3
B 22 • 2
C 22 • 32
D 23 • 32
6. What is the prime factorization of 50?
F 3 • 52
G 32 • 5
H 2 • 52
J 32 • 52
7. What is the prime factorization of 35?
A 2•3•5
B 5•7
C 32 • 5
D 32 • 7
8. What is the prime factorization of 27?
F 33
G 22 • 3
H 92
J 22 • 32
10. 20
2
13. 30
11. 32
2 •5
2
14. 44
15. 63
2
2•3•5
2
7
2 • 11
9. 57
3 •7
3•5•7
18. 110
3 • 31
21. 625
19. 80
4
2 • 5 • 11
2 •5
22. 98
4
5
23. 140
2
24. 92
2 • 23
5
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Holt Mathematics
3. 109
Composite
Prime
6. 343
Prime
7. 135
8. 180
33 • 5
13. 220
17. 2,000
24 • 53
11. 575
22 • 32 • 52
14. 350
22 • 5 • 11
6
2
12. 90
52 • 23
15. 495
2 • 52 • 7
18. 1,040
2 •5
22 • 54
2 • 5 • 13
6
Holt Mathematics
19. 1,650
24 • 5 • 13
16. 480
4
3
2
9
2
3
3
The prime factorization of 36 is
2 • 2 • 3 • 3, or 22 • 32.
Use a factor tree to find the prime factorization.
25 • 3 • 5
1. 20
2. 28
3. 54
4. 63
20. 3,000
2 • 3 • 52 • 11
2
36
Keep factoring until all
the factors are prime.
3
The prime factorization of 18 is
2 • 3 • 3, or 2 • 32.
2 • 32 • 5
32 • 5 • 11
Use a factor tree to find the prime
factorization of 36.
18
22 • 32 • 5
Use a step diagram to find the prime factorization.
2 • 5 • 29
32. 2,500
4
Use a factor tree to find the prime
factorization of 18.
73
10. 900
31. 1,040
3
To write the prime factorization of a number, write the number as
the product of only prime numbers. A prime number has only two
factors, itself and 1.
4. 73
Write the prime factorization of each number.
9. 290
22 • 5 • 11
5 • 29
Review for Mastery
3-1 Prime Factorization
2. 117
22 • 3 • 7
3
28. 220
2
LESSON
Tell whether each number is prime or composite.
5. 84
30. 1,000
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
Practice C
3-1 Prime Factorization
Prime
27. 725
495
LESSON
1. 91
23 • 3 • 7
33. The prime factorization of a number is 32 • 5 • 11. What is
the number?
2
2 •5•7
24. 168
2 • 5 • 37
5 • 103
2•3 •5
23 • 32
23. 370
26. 515
2
2•3•7
20. 72
22 • 3 • 5
24 • 32
29. 450
2•3•7
2
2•7
22. 144
2
2 • 13
19. 60
7 • 13
2 • 31
20. 42
16. 42
2
2•7
2
5 • 19
15. 52
18. 91
25. 124
12. 95
23 • 11
2
23 • 7
2 •7
Composite
11. 88
14. 98
21. 56
2
Prime
72
13. 105
Use a step diagram to find the prime factorization.
17. 93
10. 49
3 • 19
16. 28
2
8. 119
Composite
22 • 17
5
Prime
7. 83
Write the prime factorization of each number.
12. 49
2
5
Composite
4. 79
Composite
6. 121
17. 68
Use a factor tree to find the prime factorization.
3. 52
Prime
5. 96
Choose the letter for the best answer.
9. 25
2. 41
23 • 3 • 53
22 • 5
5
21. The prime factorization of a number is 2 • 3 . What is
the number?
22 • 7
2 • 33
Use a step diagram to find the prime
factorization of 75.
Use a step diagram to find the prime
factorization of 60.
972
2|60
2|30
3|15
5|5
1
22. You can factor 150 as 15 • 10. List four other ways can you
factor 150.
5 • 30; 3 • 50; 6 • 25; 2 • 75
23. A number x is a prime factor of 65 and 104. What is the number?
1) The divisors must be prime numbers.
2) Keep dividing until the quotient is 1.
3) The divisors are the factors in the
prime factorization.
The prime factorization of 60 is
2 • 2 • 3 • 5, or 22 • 3 • 5.
13
32 • 7
3|75
5|25
5|5
1
The prime factorization of 75 is
3 • 5 • 5, or 3 • 52.
Write the composite number for each prime factorization.
24. 25 • 52
800
25. 33 • 5 • 11
26. 43 • 7 • 13
1,485
5,824
27. 28 • 35
Use a step diagram to find the prime factorization.
62,208
5. 48
28. The prime factors of a number are all the prime numbers
between 20 and 30. No factor is repeated. What is the number?
24 • 3
667
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
Copyright © by Holt, Rinehart and Winston.
7
6. 24
Holt Mathematics
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
63
7. 40
23 • 3
8. 98
23 • 5
8
2 • 72
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Holt Mathematics