Download HINT You can start a factor tree with any two factors of the number

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Transcript 
Lesson: Prime Factorization
A prime number is a whole number greater than 1 whose only factors are
1 and itself.
A composite number is a whole number greater than 1 that has
factors other than 1 and itself.
You can write any composite number as a
product of prime numbers, which is called its prime factorization.
EXAMPLE 1
Tell whether the numbers 19 and 21 are prime or composite.
The only factors of 19 are 1 and 19. So, 19 is prime.
The factors of 21 are 1, 3, 7, and 21. So, 21 is composite.
EXAMPLE 2
Write the prime factorization of 60.
Use a diagram called a factor tree. Write 60 at the top. Draw two branches
and write 60 as the product of two factors. Continue to draw branches
until all the factors are prime numbers. Here are two factor trees for 60.
HINT
You can start a
factor tree with any
two factors of the
number.
Both factor trees show that the
prime factorization of 60 is 2 x 2 x 3 x 5.
Practice:
List all factors of the number. Tell whether it is prime or composite.
1. 13
2. 27
3. 32
4. 41
5. 49
6. 55
Draw a factor tree for the number. Write its prime factorization.
7. 36
8. 50
9. 54
_______________
_______________
_______________
Prime factorization
Prime factorization
Prime factorization
Name ___________________________________Class______________
Date_________________________
Math-homework
List all factors of the number. Tell whether it is prime or composite.
1. 16
2. 42
3. 23
4. 35
5. 39
6. 26
Draw a factor tree for the number. Write its prime factorization.
7. 30
8. 24
9. 63
10. 44
11. 81
12. 100
Tell whether each statement is true or false. Explain your answer.
13. Every prime number besides 2 is an odd number. _________________
_____________________________________________________________
14. Every positive even number besides 2 is composite. _______________
_____________________________________________________________
15. Every odd number greater than 1 is prime. _______________________
_____________________________________________________________
16. List the first 20 prime numbers.
Remember: The number 1 is neither prime nor composite.
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