GCF
The greatest common factor of 13 and 39
The factors of 13 are: 1, 13
The factors of 39 are: 1, 3, 13, 39
Then the greatest common factor is 13.
Factor Pairs of 7
1 and 7
The LCM of 4 and 10
Multiples of 4:
4, 8, 12, 16, 20, 24, 28
Multiples of 10:
10, 20, 30, 40
LCM= 20
List the first 5 multiples of 4
4, 8, 12, 16, 20
What is a prime number?
A number whose only factors are only 1 and itself.
The greatest common factor of 10 and 30
The factors of 10 are: 1, 2, 5, 10
The factors of 30 are: 1, 2, 3, 5, 6, 10, 15, 30
Then the greatest common factor is 10.
Factor Pairs of 21
1 and 21
3 and 7
The LCM of 5 and 25
Multiples of 5:
5, 10, 15, 20, 25, 30, 35
Multiples of 25:
25, 50, 75
LCM= 25
List the first 5 multiples 8
8, 16, 24, 32, 40
What is a composite number?
A number with more factors than 1 and itself.
The greatest common factor of 42 and 70
The factors of 42 are: 1, 2, 3, 6, 7, 14, 21, 42
The factors of 70 are: 1, 2, 5, 7, 10, 14, 35, 70
Then the greatest common factor is 14.
Factor Pairs of 20
1 and 20
2 and 10
4 and 5
The LCM of 3 and 5
Multiples of 3:
3, 6, 9, 12, 15, 18, 21
Multiples of 5:
5, 10, 15, 20, 25
LCM = 15
List the first 5 multiples of 12
12, 24, 36, 48, 60
Is 39 a prime or composite number?
Composite
The greatest common factor of 4, 24, 48
The factors of 4 are: 1, 2, 4
The factors of 24 are: 1, 2, 3, 4, 6, 8, 12, 24
The factors of 48 are: 1, 2, 3, 4, 6, 8, 12, 16, 24, 48
Then the greatest common factor is 4.
Factor Pairs of 63
1 and 63
3 and 12
7 and 9
The LCM of 2, 6, 9
Multiples of 2:
2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22
Multiples of 6:
6, 12, 18, 24, 30
Multiples of 9:
9, 18, 27, 36
LCM= 18
List the next nine multiples of 9
9, 18, 27, 36, 45, 54, 63, 72, 81, 90
Is 31 prime or composite?
Prime
The greatest common factor of 26, 39 and 65
The factors of 26 are: 1, 2, 13, 26
The factors of 39 are: 1, 3, 13, 39
The factors of 65 are: 1, 5, 13, 65
Then the greatest common factor is 13.
Factor pairs of 40
1 and 40
2 and 20
4 and 10
5 and 8
The LCM of 5, 10, 15
Multiples of 5:
5, 10, 15, 20, 25, 30, 35, 40
Multiples of 10:
10, 20, 30, 40, 50
Multiples of 15:
15, 30, 45, 60
LCM= 30
List the next nine multiples of 10
10, 20, 30, 40, 50, 60, 70, 80, 90
List the composite numbers between 19 and 30
20, 21, 22, 24, 25, 26, 27, 28