Write factor pairs for each number.
Use divisibility tests to help you!
40
72
57
1 x 40
2 x 20
4 x 10
5x8
1 x 72
2 x 36
3 x 24
4 x 18
6 x 12
8x9
1 x 57
3 x 19
Write factor pairs for each number.
Use divisibility tests to help you!
12
20
37
1 x 12
2x6
3x4
1 x 20
2 x 10
4x5
1 x 37
PRIME
PRIME NUMBERS

1
A whole number with exactly 2 factors,
1 and itself
2
3
4
5
6
7
8
9 10
11 12 13 14 15 16 17 18 19 20
Make a prime factor tree for each
number.
24
4
x
60
6
2 x 2 x 2 x 3
24 = 2 x 2 x 2 x 3
3
24 = 2 x 3
6
x 10
2 x 3x 2 x 5
60 = 2 x 2 x 3 x 5
2
60 = 2 x 3 x 5
You can use prime factorizations to find
the GCF or to simplify fractions.
24
4
x
60
6
6
2 x 2 x 2 x 3
24
60
2x2x2x3
2x2x3x5
x 10
2 x 3x 2 x 5
2
5
GCF
2 x 2 x 3 = 12
Make a prime factor tree for each number
to find the GCF.
36
6
x
54
6
2 x 3 x 2 x 3
36 = 2 x 2 x 3 x 3
54 = 2 x 3 x 3 x 3
6
x 9
2 x 3x 3 x 3
GCF
2 x 3 x 3 = 18
Make prime factor trees for each number. Use the
prime factorizations to find the GCF and to
simplify the fraction.
40
4
x
56
10
2
2 x 2 x 2 x 5
x 28
4 x 7
2x 2
40
56
=
2x2x2x5
2x2x2x7
=
5
7
GCF
2x2x2=8
List the factors of 15.
15
1 x 15
3x5
List the multiples of 15.
15, 30, 45, 60, 75, …
List the first 5 multiples of each number.
12
12, 24, 36, 48, 60
16
16, 32, 48, 64, 80
24
24, 48, 72, 96, 120
Use the LCM to get a common
denominator.
12, 24, 36, 48, 60
7
28
=
48
12
16
16, 32, 48, 64, 80
5
15
=
48
16
24
24, 48, 72, 96, 120
12
Use the LCM to get a common
denominator.
12
12, 24, 36, 48, 60
16
16, 32, 48, 64, 80
5
15
=
48
16
24
24, 48, 72, 96, 120
9
18
=
48
24
Use the LCM to get a common
denominator.
12
12, 24, 36, 48, 60
16
16, 32, 48, 64, 80
24
24, 48, 72, 96, 120
5
10
=
24
12
11 = 11
24
24
List the factors of 32.
32
1 x 32
2 x 16
4x8
Make a prime factor tree for 32.
32
4
2 x 2
x
32
8
2
2 x 4
x 16
4
2 x 2
x
4
2x 2x 2x 2
32 = 2 x 2 x 2 x 2 x 2
32 = 25
Use the prime factorization to simplify
12
32
12
2
x
32
6
2
x 16
2 x 3
4
x
4
2x 2x 2x 2
12 = 2 x 2 x 3
32 = 2 x 2 x 2 x 2 x 2
3
8
What is the GCF?
4
List factor pairs to find the GCF.
18
30
1 x 18
2x9
3x6
1 x 30
2 x 15
3 x 10
5x6
Use the GCF to simplify:
18
30
GCF = 6
÷6
÷6
3
10
Write the expressions using exponents.
2
2x3x3x5x5= 2x3 x5
5 x 5 x 5 x 7 x 7 = 53 x 72
2
Find the LCM.
8
10
8, 16, 24, 32, 40
10, 20, 30, 40
3
15
=
40
8
4
16
=
40
10