Transcript Factors/Multiples

Prime Numbers
Composite Numbers
Factors
Prime Factorization (Factor Trees)
Multiples
Least Common Multiple
Greatest Common Factor
Divisibility Rules
Examples
to support
Examples that
do not work.
Number
It is divisible if…
2
A number ends in
0, 2, 4, 6, 8
3
The sum of the digits is
divisible by 3
3, 6, 12, 135
142, 17, 23
4
If the last two digits are
divisible by 4 or the
number ends in 00.
44, 100, 124
120, 112
41, 77, 38
114, 14
5
If the number ends in 5 or
0.
10, 25, 55, 135
41, 77, 88
6
If the number is divisible
by 2 and 3.
6, 12, 24,
19, 44, 50
9
If the sum of the digits is
divisible by 9.
9, 18, 189, 981
38, 980, 98
10
If the number ends in 0.
10, 20, 30, 1090
125, 38, 88
10, 12, 14
36, 98
15, 17, 79
A PRIME number is a number that has only two
factors: 1 and itself.
Example:
2:
only 1 and 2 will go into 2
3:
only 1 and 3 will go into 3
5:
only 1 and 5 will go into 5
Other prime numbers are :
7, 11, 13, 17, 19, 23, and many more!
Greatest common Factor (GCF)
To find the GCF do the following:
Step 1: List all the factors for each number
Step 2: Find the largest factor these two numbers have in common
Example:
Find the GCF for 60 and 72
60: 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60
72: 1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36, 72
The largest number 60 and 72 have in common is 12, therefore the GCF = 12
Least Common Multiple
To find the least common multiple do the following:
Step 1: List the multiples for each number
Step 2: Find the smallest number they have in common other
than zero.
Example:
Find the LCM for 7 and 5
7: 0, 7, 14, 21, 28, 35, 42, …
5: 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, …
List the factors each number. Then check your answer by
clicking the “CHECK” button.
1. List the factors of 8:
2. List the factors of 10:
3. List the factors of 4:
4. List the factors of 20:
5. List the factors of 16:
6. List the factors of 25:
7. List the factors of 100:
8. List the factors of 3:
REVIEW
CHECK
List the factors each number. Then check your answer by clicking
the “CHECK” button.
1. List the factors of 8: 1, 2, 4, 8
2. List the factors of 10: 1, 2, 5, 10
3. List the factors of 4: 1, 2, 4
4. List the factors of 20: 1, 2, 4, 5, 10, 20
5. List the factors of 16: 1, 2, 4, 8, 16
6. List the factors of 25: 1, 5, 25
REVIEW
7. List the factors of 100: 1, 2, 4, 5, 10, 20, 25, 50, 100
8. List the factors of 3: 1, 3
Back to Quiz
Composite numbers are numbers that have
more than two factors.
Example:
4: 1, 2 and 4 go into 4
6: 1, 2 , 3 and 6 go into 6
8: 1, 2, 4, and 8 go into 8.
QUIZ
Factors are numbers that go into another number. To find
the factors of a number, find the pairs.
Example:
Factors of 20
Factors of 50:
1 x 20
1 x 50
2 x 10
2 x 25
4 x
5 x 5
5
20: 1, 2, 4, 5, 10, 20
Then write them in order from least to greatest!
50: 1, 2, 5, 25, 50
Then write them in order from least to greatest!
Remember: A factor will never be larger than the number itself.
QUIZ
Factor Trees are used to find the PRIME
FACTORIZATION of a number.
70
Circle the number if
it is prime
35
5
2
7
Prime Factorization of
70 is: 2 x 5 x 7
QUIZ
Multiples are all the numbers a number will
go into. Multiples are infinite!
Examples:
Multiples of :
5: 0, 5, 10, 15, 20, …
3: 0, 3, 6, 9, 12, 15, 18, …
20: 0, 20, 40, 60, …
0 is the first multiple
of every number.
Multiples are infinite,
so you must end each
line with …
to show infinity.
List the prime factorization for each number. Then check your
answer by clicking the “CHECK” button.
1. 72
2. 50
3. 100
4. 90
5. 20
6. 15
CHECK
REVIEW
1. 72:
2. 50:
3
2
2
5
3. 100:
5
4. 90:
3
5. 20:
2
6. 15:
3
2
2
2
x
3
x
2
x
2
x
5
x
5
x
5
2
2
x
2
Back To
The Quiz
REVIEW
List the multiples for each number. Then check your answer by
clicking the “CHECK” button.
1. List the multiples of 8:
2. List the multiples of 10:
3. List the multiples of 4:
4. List the multiples of 20:
5. List the multiples of 16:
6. List the multiples of 25:
CHECK
7. List the multiples of 100:
8. List the multiples of 3:
REVIEW
1. List the multiples of 8: 0, 8, 16, 24, 32, …
2. List the multiples of 10: 0, 10, 20, 30, 40,…
3. List the multiples of 4: 0, 4, 8, 12, 16, …
4. List the multiples of 20: 0, 20, 40, 60, 80, …
5. List the multiples of 16: 0, 16, 32, 48, 64, …
6. List the multiples of 25: 0, 25, 50, 75, 100, …
7. List the multiples of 100: 0, 100, 200, 300, 400, …
8. List the multiples of 3: 0, 3, 6, 9, 12, …
BACK TO THE QUIZ
REVIEW