Prime and Composite Numbers
DEFINITION:
A prime number is a whole number that only has two factors which are itself and one.
A composite number has factors in addition to one and itself.
RULES TO REMEMBER ABOUT PRIME AND COMPOSITE:
(Citation: http://www.aaamath.com/fra63ax2.htm (Links to an external site.))
FACTORS
DEFINITION:
Factors are the numbers you multiply together to get another number.
Click HERE for more information on FACTORS (Links to an external site.).
FACTOR TREES:
Factor Trees help us to identify all of the factors for a number. To watch a video on how to create a factor tree,click HERE! (Links to an external site.)
Finding the Greatest Common Factor:
The GCF (Greatest Common Factor) is the largest factor that two or more numbers have in common.
There are TWO ways you can find the Greatest Common Factor. HERE (Links to an external site.) is a tutorial on BOTH methods.
ONE way to find the GCF: Factor Trees
Step 1: Create a Factor Tree for both (or more) numbers.
Step 2: Find all of the factors that are common in all of the factor trees.
Step 3: If there is more than one common factor, multiply the numbers together.
Step 4: This is your GCF!
A SECOND way to find the GCF: Factor List
Step 1: Create a list of ALL factors for each number.
Step 2: Circle the greatest factor that appears on both lists.
Step 3: This is your GCF!
Click Here to take a lesson (Links to an external site.) on Finding the Greatest Common Factor.
Multiples
A multiple is the result of multiplying a number by a whole number. For example, to find a multiple of a number, multiply that number by any whole number.
EXAMPLE: Multiples for the number 5 can be found by taking 5 x 1, 5 x 2, 5 x 3, 5 x 4, etc.
Multiples of the number 5 are 5, 10, 15, 20, 25, etc.
Click HERE for another explanation of Multiples. (Links to an external site.)
LEAST COMMON MULTIPLE:
The LCM (Least Common Multiple) is the smallest multiple that two or more numbers have in common.
How to find the LCM:
Step 1: List several multiples of each number.
Step 2: Check to see if there are any common numbers between the lists.
Step 3: If there are no common multiples, continue writing multiples of each number until you find a number that is the same. You may have a very long list or a very short list!
Step 4: Once you find the same number on both lists, you have found the Least Common Multiple. Remember, you may find more than one common multiple but you want the smallest (least) common multiple.
Videos for finding the LCM: (Links to an external site.) When you click on this, on the left column you can pick a different method using factor trees.
DEFINITION:
A prime number is a whole number that only has two factors which are itself and one.
A composite number has factors in addition to one and itself.
RULES TO REMEMBER ABOUT PRIME AND COMPOSITE:
- The numbers 0 and 1 are neither prime nor composite.
- All even numbers are divisible by two and so all even numbers greater than two are composite numbers.
- All numbers that end in five are divisible by five. Therefore all numbers that end with five and are greater than five are composite numbers.
(Citation: http://www.aaamath.com/fra63ax2.htm (Links to an external site.))
FACTORS
DEFINITION:
Factors are the numbers you multiply together to get another number.
Click HERE for more information on FACTORS (Links to an external site.).
FACTOR TREES:
Factor Trees help us to identify all of the factors for a number. To watch a video on how to create a factor tree,click HERE! (Links to an external site.)
Finding the Greatest Common Factor:
The GCF (Greatest Common Factor) is the largest factor that two or more numbers have in common.
There are TWO ways you can find the Greatest Common Factor. HERE (Links to an external site.) is a tutorial on BOTH methods.
ONE way to find the GCF: Factor Trees
Step 1: Create a Factor Tree for both (or more) numbers.
Step 2: Find all of the factors that are common in all of the factor trees.
Step 3: If there is more than one common factor, multiply the numbers together.
Step 4: This is your GCF!
A SECOND way to find the GCF: Factor List
Step 1: Create a list of ALL factors for each number.
Step 2: Circle the greatest factor that appears on both lists.
Step 3: This is your GCF!
Click Here to take a lesson (Links to an external site.) on Finding the Greatest Common Factor.
Multiples
A multiple is the result of multiplying a number by a whole number. For example, to find a multiple of a number, multiply that number by any whole number.
EXAMPLE: Multiples for the number 5 can be found by taking 5 x 1, 5 x 2, 5 x 3, 5 x 4, etc.
Multiples of the number 5 are 5, 10, 15, 20, 25, etc.
Click HERE for another explanation of Multiples. (Links to an external site.)
LEAST COMMON MULTIPLE:
The LCM (Least Common Multiple) is the smallest multiple that two or more numbers have in common.
How to find the LCM:
Step 1: List several multiples of each number.
Step 2: Check to see if there are any common numbers between the lists.
Step 3: If there are no common multiples, continue writing multiples of each number until you find a number that is the same. You may have a very long list or a very short list!
Step 4: Once you find the same number on both lists, you have found the Least Common Multiple. Remember, you may find more than one common multiple but you want the smallest (least) common multiple.
Videos for finding the LCM: (Links to an external site.) When you click on this, on the left column you can pick a different method using factor trees.
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