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101740_6FactorsandPrimeandCompositeNumbers.pdf
Factors, Prime Numbers &
Composite Numbers
by Carol Edelstein
Definition
•Product- An answer to a multiplication problem.
7 x 8 = 56
Product
Definition
•Factor- a number that is multiplied by another to give a product.
7 x 8 = 56
Factors
Definition
•Factor- a number that divides evenly into another number.
56 ÷ 8 = 7
Factors
Test yourself...
What are the factors and products?
1) 6 x 7 = 422) 63 ÷9 = 73) 8 x 5 = 40Factors: 6 and 7Product: 42
Factors: 7 and 9
Product: 63
Factors: 5 and 8
Product: 40
Example: 7 is primebecause the only numbers that will divide into it evenly are 1 and 7.
Definition
•Prime Number- a number that has only two factors, itself and 1. Examples of Prime Numbers2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37... Example: The number 8. The factors of 8 are 1, 2, 4, 8.
Definition
•Composite number- a number that has more than two factors. Examples of Composite Numbers4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, ...
One is special because . . .
One is not prime.
(because it doesnot have exactlytwo differentfactors).
One is not Composite.
(because it doesnot have morethan 2 factors).
Definition
•Prime Factorization- A way to write a composite number as the product of its prime factors.
2 x 2 x 3= 12
or
22x 3 = 12
How to do a Prime Factorization
48
Step 1 -Write down any
composite number. - - Factor Tree Method - -
Step 2 -Start dividing by
the prime #s (start with 2).
If the composite number is divisible
by 2, write it down and find the next factor.
If not, check if the factor is evenly
divisible by 3, 5, 7, 9, etc.
2 x 24
How to do a Prime Factorization
48
Step 3 -Check the factors.
If they are prime, you are done.
If they are not, proceed to Step 4.
- - Factor Tree Method - -
Step 4 -Continue dividing.
If one of the factors is
divisible by 2, write it down and find the next factor.
If not, check if the factor is evenly
divisible by 3, 5, 7, 9, etc.
2 x 242 x 2 x 12
How to do a Prime Factorization
48
Step 5 -Check the factors.
If they are prime, proceed to Step 6.
If they are not, repeat Step 4.
- - Factor Tree Method - -
2 x24
2 x 2 x122 x2 x2 x6
How to do a Prime Factorization
48
Step 5 -Check the factors.
If they are prime, proceed to Step 6.
If they are not, repeat Step 4.
- - Factor Tree Method - -
Step 6 -Write the
Prime Factorization in
Exponential Form.
2 x242 x 2 x122 x2 x2 x62 x2 x2 x2 x3
22224 4 4 4 xxxx3333= 48
Find the Prime Factorization
44442 x 2
2 2= 4
Prime Factorization
Prime Factorization
in Exponential Form
Find the Prime Factorization
62 x 3====6
Prime Factorization
Find the Prime Factorization
273 x 9
3 3= 27
3 x 3 x 3
Prime Factorization
Prime Factorization
in Exponential Form
Find the Prime Factorization
122 x 6
22x 3 = 12
2 x 2 x 3
Prime FactorizationPrime Factorization
in Exponential Form
Find the Prime Factorization
182 x 9
2 x 3
2= 182 x 3 x 3
Prime Factorization Prime Factorization
in Exponential Form
You Have Options
The following screens illustrate another
method that you can use to find the Prime Factorization of a Composite Number. Try it! You may like it better.
How to do a Prime Factorization
18
Step 1 -Write down any
composite number. - - Ladder Method - -
Step 2 -Start dividing by the
prime #s (start with 2).
If the composite number is divisible by 2,
write it on the left of the L and write the other factor below the original composite #.
If not, check if the number is evenly divisible
by 3, 5, etc. 2 9
How to do a Prime Factorization
18
Step 3 -Check the factors.
If they are prime, proceed to Step 6.
If not, continue the process.
- - Ladder Method - -
Step 4 -Continue dividing the # on the next
rung of the ladder by the prime #s (start with 2). 2 93
3
Step 5 -Repeat this process until the # on
the next rung of the ladder is prime. Prime #
How to do a Prime Factorization
18- - Ladder Method - -
2 93
3
Prime
Factorization
2x 3x 3
Prime Factorization
in Exponential Form 2x 32
Step 6 -Write the
Prime Factorization in
Exponential Form.
56- - Ladder Method - -
2 7
Prime
Factorization
2x 2x 2 x 7
Prime Factorization
in Exponential Form
23 x 728
2 142
Prime #
Find the Prime Factorization
Summary
• One is not a prime orcomposite number. • Two is the only even prime number. • Not all odd numbers are prime. (examples: 9, 15, 21, 27, 33, 35, ...) • All composite numbers can be written as product of prime numbers.
The End