Download Factors - InforMNs

REVIEW OF 4.1­4.3
Factors
What is
factoring
?
Factoring a number involves breaking it down into smaller numbers that can be multiplied together to get the original number.
Example: 4 x 2 = 8
Factors of 8 are 4 and 2.
Sometimes, a number can be factored into different combinations.
Example: 2 x 2 x 2 = 8
Factors of 8 are also 2, 2, and 2.
Nov 14 ­ 9:33 AM
Prime Numbers
What is a
prime number
A prime number
and the number itself.
is a whole number that has exactly two factors: 1 Example:
The factors of 2 are 1 and 2. This makes 2 a prime number
2
1
What are the ?
x
2
prime numbers
Why is 12 not a .
prime number
between 1 and 30?
?
12
3
6
x
x
2
2
12 is not a prime number because it has more factors than 1 and itself.
Move box to reveal answer.
Nov 11 ­ 2:45 PM
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REVIEW OF 4.1­4.3
Composite Numbers
What is a
composite number
A composite number
two or more factors.
is a number that can be broken down into Example:
Factors of 16 = 1, 2, 4, 8, 16.
16 is a composite number
What are the ?
.
composite numbers between 1 and 30?
Nov 14 ­ 9:24 AM
Prime Factorization
What is
prime factorization
?
Prime factorization
breaks down a number's factors into prime numbers. This can be done using factor trees.
24
x
6
3 x 2
Once you have a prime number
4
The prime factors 2, 2, 3.
of 24 are 2, HINT: Always write factors from smallest to largest.
2 x 2
, you stop factoring.
HINT: No matter how you break up a number, the prime factors always end up the same. 56
56
28
14
7
8
2
2
2
4
2
Prime factors are 2, 2, 2, 7.
2
7
2
Prime factors are 2, 2, 2, 7.
Nov 11 ­ 2:56 PM
2
REVIEW OF 4.1­4.3
Use factor trees to break each number
into its prime factors.
18
41
66
81
Nov 11 ­ 3:41 PM
16
36
32
60
72
100
Nov 13 ­ 2:53 PM
3
REVIEW OF 4.1­4.3
Greatest Common Factor (GCF)
What is the
greatest common factor
?
The greatest common factor
of two numbers is the largest factor shared by both. You determine the GCF by calculating all the factors of both numbers and finding the largest one that is a factor of both.
Example: What is the GCF of 44 and 66?
Factors of 44: 1, 2, 4, 11, 22, 44
Factors of 66: 1, 2, 3, 11, 22, 33, 66
The greatest common factor
of 44 and 66 is 22.
Nov 11 ­ 3:40 PM
Find the GCF of the following number pairs:
Factors of 18
Factors of 24
.
The greatest common factor is Factors of 36
Factors of 54
.
The greatest common factor is Factors of 8
Factors of 80
.
The greatest common factor is Factors of 60
Factors of 18
.
The greatest common factor is Nov 13 ­ 2:35 PM
4
REVIEW OF 4.1­4.3
Greatest Common Factor (GCF)
You can also find the
prime factorization
Example:
.
54
36
6
3 x 2
36
54
GCF of two numbers using
x
9
6
3 x 2
x
6
3 x 3 3 x 2
2, 2, 3, 3
2, 3, 3, 3
What prime factors do 36 and 54 have in common?
36
54
2, 2, 3, 3
2, 3, 3, 3
Multiply the common prime factors together to find the 2 x 3 x 3 = 18
The GCF of 36 and 54 is 18.
GCF.
Nov 14 ­ 7:48 AM
Find the GCF of the following number pairs
using the prime factorization method.
8 and 24
45 and 15
40 and 12
32 and 60
15 and 18
45 and 60
Nov 14 ­ 8:16 AM
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