Transcript Prime Factors - Skyline R2 School

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Objective
Find the prime factorization of a composite number
Vocabulary
Factor
Two or more numbers that are multiplied
3  4
both 3 and 4 are factors
Vocabulary
Prime number
A whole number that has exactly 2 unique
factors, 1 and the number itself
2 Factors 1 & 2
3 Factors 1 & 3
5 Factors 1 & 5
13 Factors 1 & 13
Most Common Prime Numbers:
2, 3, 5, 7, 11, 13, 17,
23, 29, 31, 37, 41, 43, 47
Vocabulary
Composite number
A number greater than 1 with more than 2
factors
4
Factors 1, 2, & 4
12
Factors 1, 2, 3, 4, 6, & 12
Vocabulary
Prime factorization
Expressing a composite number as a product
of prime
12 = 22  3
54 = 2  33
Example 1 Identify Prime and Composite Numbers
Example 2 Identify Prime and Composite Numbers
Example 3 Find Prime Factorization
Tell whether 13 is prime, composite, or neither.
The factors of 13:
1 and 13
Has 2 factors which are 1 and the number itself
Fits the definition of “prime” number
Answer:
prime
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Tell whether 35 is prime, composite, or neither.
Answer:
composite
1/3
Tell whether the number 20 is prime, composite, or
neither.
The factors of 20:
1 and 20,
2 and 10,
4 and 5
20 has more than 2 factors
Fits the definition of “composite” number
Answer: composite
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Tell whether the number 41 is prime, composite, or
neither.
Answer: prime
2/3
Find the prime factorization of 96.
Write the number
96
Draw prime factorization brackets
Decide on prime number that will go
evenly into 96
Think about divisibility rules
Note: If even consider 2
If ones digits is 0 or 5
consider 5
3/3
Find the prime factorization of 96.
2 96
48
The one’s digit is 6 which is
divisible by 2
Place the prime number 2 to the
left of the bracket
Divide 96 by 2 and place the answer
below the bracket
Determine if 48 is a prime number
3/3
Find the prime factorization of 96.
The one’s digit is 8 which is divisible
by 2
2 96
2 48
24
48 is not prime so place another
prime factorization bracket under 48
Since 48 is divisible by 2, place the
2 to the left of the bracket
Divide 48 by 2 and place the answer
below the bracket
Determine if 24 is a prime number
3/3
Find the prime factorization of 96.
2 96
2 48
2 24
12
The one’s digit is 4 so 24 is divisible
by 2
24 is not prime so place another
prime factorization bracket under 24
Since 24 is divisible by 2, place the
2 to the left of the bracket
Divide 24 by 2 and place the answer
below the bracket
Determine if 12 is a prime number
3/3
Find the prime factorization of 96.
2 96
2 48
2 24
2 12
6
The one’s digit is 2 so 12 is divisible
by 2
12 is not prime so place another
prime factorization bracket under 12
Since 12 is divisible by 2, place the
2 to the left of the bracket
Divide 12 by 2 and place the answer
below the bracket
Determine if 6 is a prime number
3/3
Find the prime factorization of 96.
The one’s digit is 6 so 6 is divisible
by 2
2 96
2 48
2 24
2 12
2 6
3
6 is not prime so place another
prime factorization bracket under 6
Since 6 is divisible by 2, place the
2 to the left of the bracket
Divide 6 by 2 and place the answer
below the bracket
Determine if 3 is a prime number
3/3
Find the prime factorization of 96.
The factors of 3 are
1 and 3
2 96
2 48
3 fits the definition of a prime number
2 24
2 12
2 6
Finished prime factoring so now write
answer
3
3/3
Find the prime factorization of 96.
Write the smallest prime number
which in this case is 2
2 96
Circle all the 2’s that were used in
prime factoring, counting as you go
2 48
2 24
2 12
2 6
Since there were 5 two’s , place an
exponent of 5 with the 2 in your
answer
3
2
5
3/3
Find the prime factorization of 96.
Next put a multiplication sign
Note: Do not use “x” for
multiplication
2 96
2 48
2 24
2 12
2 6
Write the next smallest prime
number which in this case is 3
Circle all the 3’s that were used in
prime factoring, counting as you go
3
5
2  3
3/3
Find the prime factorization of 96.
Since there is only 1 three , do not
put an exponent
2 96
2 48
2 24
2 12
2 6
3
Answer:
You are finished after you circle your
answer! Yippee
Note: Any prime number can be
used. If you start with an odd
number, you will not start with 2
5
2  3
3/3
*
Find the prime factorization of 72.
Answer: 23  32
3/3
Assignment
Lesson 1:3
Prime Factors
14 - 46 Even