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Learn how to find the prime factorization of composite numbers in this lesson. Identify prime and composite numbers, and practice finding the factors and prime factorization.
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Lesson 3 Contents Objective Find the prime factorization of a composite number
Lesson 3 Contents Vocabulary Factor Two or more numbers that are multiplied 3 4 both 3 and 4 are factors
Lesson 3 Contents Vocabulary Prime number A whole number that has exactly 2 unique factors, 1 and the number itself • Factors 1 & 2 • Factors 1 & 3 • 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
Lesson 3 Contents 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
Lesson 3 Contents Vocabulary Prime factorization Expressing a composite number as a product of prime 12 = 22 3 54 = 2 33
Lesson 3 Contents Example 1Identify Prime and Composite Numbers Example 2Identify Prime and Composite Numbers Example 3Find Prime Factorization
Example 3-1a 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 1/3
Example 3-1b Tell whether 35 is prime, composite, or neither. Answer: composite 1/3
Example 3-2a 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 2/3
Example 3-2b Tell whether the number 41 is prime, composite, or neither. Answer: prime 2/3
Example 3-3a 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
Example 3-3a Find the prime factorization of 96. The one’s digit is 6 which is divisible by 2 2 96 48 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
Example 3-3a Find the prime factorization of 96. The one’s digit is 8 which is divisible by 2 2 96 48 is not prime so place another prime factorization bracket under 48 2 48 24 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
Example 3-3a Find the prime factorization of 96. The one’s digit is 4 so 24 is divisible by 2 2 96 24 is not prime so place another prime factorization bracket under 24 2 48 24 2 Since 24 is divisible by 2, place the 2 to the left of the bracket 12 Divide 24 by 2 and place the answer below the bracket Determine if 12 is a prime number 3/3
Example 3-3a Find the prime factorization of 96. The one’s digit is 2 so 12 is divisible by 2 2 96 12 is not prime so place another prime factorization bracket under 12 2 48 24 2 Since 12 is divisible by 2, place the 2 to the left of the bracket 2 12 6 Divide 12 by 2 and place the answer below the bracket Determine if 6 is a prime number 3/3
Example 3-3a Find the prime factorization of 96. The one’s digit is 6 so 6 is divisible by 2 2 96 6 is not prime so place another prime factorization bracket under 6 2 48 24 2 Since 6 is divisible by 2, place the 2 to the left of the bracket 2 12 2 6 Divide 6 by 2 and place the answer below the bracket 3 Determine if 3 is a prime number 3/3
Example 3-3a Find the prime factorization of 96. The factors of 3 are 1 and 3 2 96 3 fits the definition of a prime number 2 48 24 2 Finished prime factoring so now write answer 2 12 2 6 3 3/3
Example 3-3a 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 24 2 Since there were 5 two’s , place an exponent of 5 with the 2 in your answer 2 12 2 6 3 5 2 3/3
Example 3-3a Find the prime factorization of 96. Next put a multiplication sign Note: Do not use “x” for multiplication 2 96 2 48 Write the next smallest prime number which in this case is 3 24 2 2 12 Circle all the 3’s that were used in prime factoring, counting as you go 2 6 3 5 2 3 3/3
Example 3-3a Find the prime factorization of 96. Since there is only 1 three , do not put an exponent 2 96 2 48 You are finished after you circle your answer! Yippee 24 2 2 12 Note: Any prime number can be used. If you start with an odd number, you will not start with 2 2 6 3 5 2 Answer: 3 3/3
Example 3-3b * Find the prime factorization of 72. Answer: 23 32 3/3
End of Lesson 3 Assignment