Download Lesson 3-3 - Kihei Charter STEM Academy Middle School

Name
Class
Date
Lesson 3-3
Prime Numbers and Prime Factorization
Lesson Objective
To factor numbers and to find the prime factorization of numbers
Vocabulary
A factor is All rights reserved.
A composite number is A prime number is A prime factorization is Example
a. 24
1 3 24
¬ Write each pair of factors. Start with 1.
23
,33
63
,43
,
, and
are factors. Skip 5, since 24 is not divisible by 5.
¬ Stop when you repeat factors.
The factors of 24 are
b. 35
1 3 35
,
,
,
,
,
,
, and
.
¬ Write each pair of factors. Start with 1.
37
73
¬ ¬ Skip 2, 3, and 4, since 35 is not divisible by 2, 3, or 4.
is a factor.
Skip 6, since 35 is not divisible by 6.
¬ Stop when you repeat factors.
The factors of 35 are
,
,
, and
.
© Pearson Education, Inc., publishing as Pearson Prentice Hall.
1 Finding Factors List the factors of each number.
Quick Check
1. A gift box must hold the same number of pears in each row. You have
24 pears. What arrangements can you use?
30
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Course 1 Lesson 3-3
Daily Notetaking Guide
28/09/12 3:55 PM
Name
Class
Date
Examples
2 Prime or Composite? Is the number prime or composite? Explain.
a. 61
; 61 has
b. 65
; 65 is divisible by
factors,
and
.
factors.
, so 65 has more than
3 Prime Factorization Write the prime factorization of 90 using exponents.
Method 1 Use a division ladder

2 90
¬ Divide 90 by the prime number 2. Work down.
All rights reserved.


3 ¬ The result is
3 ¬ The result is
. Divide by the prime number 3.
. Divide by 3 again.
¬ The prime factorization is
3
3
Method 2 Use a factor tree
¬ Since the sum of the digits of
© Pearson Education, Inc., publishing as Pearson Prentice Hall.
90
90 5 3 3 ®
30 5 3 3 ®
10 5 2 3 5
®
The prime factorization of 90 is
90 is 9, 90 is divisible by 3.
¬
¬ Circle the prime numbers
as you find them.
3
.
3
3
3
¬
, or
3
2
3
.
Quick Check
2. Is the number prime or composite? Explain.
a. 39
b. 47
c. 63
3. Find the prime factorization of 27.
Daily Notetaking Guide
441196_C1_Ch3_WKbk_Ver-1.indd 31
Course 1 Lesson 3-3
31
28/09/12 3:55 PM