Find HCF of 2 Numbers by using Prime Factorization

Name Grade School
Date Questions20 Score

1
Find the GCF of 5 and 10
2
Find the GCF of 6 and 15
3
Find the GCF of 10 and 8
4
Find the GCF of 12 and 20
5
Find the GCF of 14 and 21
6
Find the GCF of 9 and 12
7
Find the GCF of 16 and 20
8
Find the GCF of 30 and 45
9
Find the GCF of 24 and 30
10
Find the GCF of 15 and 9
11
Find the GCF of 18 and 27
12
Find the GCF of 8 and 12
13
Find the GCF of 9 and 12
14
Find the GCF of 6 and 8
15
Find the GCF of 8 and 10
16
Find the GCF of 12 and 15
17
Find the GCF of 12 and 18
18
Find the GCF of 12 and 16
19
Find the GCF of 6 and 9
20
Find the GCF of 24 and 36

Answers Key
1
Find the GCF of 5 and 10
5 is the GCF of 5 and 10
Factors of 5
55
1
Factors of 10
210
55
1


Factors of 5 = 5
Factors of 10 = 2 x 5
Multiply all the common factors of 5 and 10.
5 = 5
GCF(5, 10) = 5
2
Find the GCF of 6 and 15
3 is the GCF of 6 and 15
Factors of 6
26
33
1
Factors of 15
315
55
1


Factors of 6 = 2 x 3
Factors of 15 = 3 x 5
Multiply all the common factors of 6 and 15.
3 = 3
GCF(6, 15) = 3
3
Find the GCF of 10 and 8
2 is the GCF of 10 and 8
Factors of 10
210
55
1
Factors of 8
28
24
22
1


Factors of 10 = 2 x 5
Factors of 8 = 2 x 2 x 2
Multiply all the common factors of 10 and 8.
2 = 2
GCF(10, 8) = 2
4
Find the GCF of 12 and 20
4 is the GCF of 12 and 20
Factors of 12
212
26
33
1
Factors of 20
220
210
55
1


Factors of 12 = 2 x 2 x 3
Factors of 20 = 2 x 2 x 5
Multiply all the common factors of 12 and 20.
2 x 2 = 4
GCF(12, 20) = 4
5
Find the GCF of 14 and 21
7 is the GCF of 14 and 21
Factors of 14
214
77
1
Factors of 21
321
77
1


Factors of 14 = 2 x 7
Factors of 21 = 3 x 7
Multiply all the common factors of 14 and 21.
7 = 7
GCF(14, 21) = 7
6
Find the GCF of 9 and 12
3 is the GCF of 9 and 12
Factors of 9
39
33
1
Factors of 12
212
26
33
1


Factors of 9 = 3 x 3
Factors of 12 = 2 x 2 x 3
Multiply all the common factors of 9 and 12.
3 = 3
GCF(9, 12) = 3
7
Find the GCF of 16 and 20
4 is the GCF of 16 and 20
Factors of 16
216
28
24
22
1
Factors of 20
220
210
55
1


Factors of 16 = 2 x 2 x 2 x 2
Factors of 20 = 2 x 2 x 5
Multiply all the common factors of 16 and 20.
2 x 2 = 4
GCF(16, 20) = 4
8
Find the GCF of 30 and 45
15 is the GCF of 30 and 45
Factors of 30
230
315
55
1
Factors of 45
345
315
55
1


Factors of 30 = 2 x 3 x 5
Factors of 45 = 3 x 3 x 5
Multiply all the common factors of 30 and 45.
3 x 5 = 15
GCF(30, 45) = 15
9
Find the GCF of 24 and 30
6 is the GCF of 24 and 30
Factors of 24
224
212
26
33
1
Factors of 30
230
315
55
1


Factors of 24 = 2 x 2 x 2 x 3
Factors of 30 = 2 x 3 x 5
Multiply all the common factors of 24 and 30.
2 x 3 = 6
GCF(24, 30) = 6
10
Find the GCF of 15 and 9
3 is the GCF of 15 and 9
Factors of 15
315
55
1
Factors of 9
39
33
1


Factors of 15 = 3 x 5
Factors of 9 = 3 x 3
Multiply all the common factors of 15 and 9.
3 = 3
GCF(15, 9) = 3
11
Find the GCF of 18 and 27
9 is the GCF of 18 and 27
Factors of 18
218
39
33
1
Factors of 27
327
39
33
1


Factors of 18 = 2 x 3 x 3
Factors of 27 = 3 x 3 x 3
Multiply all the common factors of 18 and 27.
3 x 3 = 9
GCF(18, 27) = 9
12
Find the GCF of 8 and 12
4 is the GCF of 8 and 12
Factors of 8
28
24
22
1
Factors of 12
212
26
33
1


Factors of 8 = 2 x 2 x 2
Factors of 12 = 2 x 2 x 3
Multiply all the common factors of 8 and 12.
2 x 2 = 4
GCF(8, 12) = 4
13
Find the GCF of 9 and 12
3 is the GCF of 9 and 12
Factors of 9
39
33
1
Factors of 12
212
26
33
1


Factors of 9 = 3 x 3
Factors of 12 = 2 x 2 x 3
Multiply all the common factors of 9 and 12.
3 = 3
GCF(9, 12) = 3
14
Find the GCF of 6 and 8
2 is the GCF of 6 and 8
Factors of 6
26
33
1
Factors of 8
28
24
22
1


Factors of 6 = 2 x 3
Factors of 8 = 2 x 2 x 2
Multiply all the common factors of 6 and 8.
2 = 2
GCF(6, 8) = 2
15
Find the GCF of 8 and 10
2 is the GCF of 8 and 10
Factors of 8
28
24
22
1
Factors of 10
210
55
1


Factors of 8 = 2 x 2 x 2
Factors of 10 = 2 x 5
Multiply all the common factors of 8 and 10.
2 = 2
GCF(8, 10) = 2
16
Find the GCF of 12 and 15
3 is the GCF of 12 and 15
Factors of 12
212
26
33
1
Factors of 15
315
55
1


Factors of 12 = 2 x 2 x 3
Factors of 15 = 3 x 5
Multiply all the common factors of 12 and 15.
3 = 3
GCF(12, 15) = 3
17
Find the GCF of 12 and 18
6 is the GCF of 12 and 18
Factors of 12
212
26
33
1
Factors of 18
218
39
33
1


Factors of 12 = 2 x 2 x 3
Factors of 18 = 2 x 3 x 3
Multiply all the common factors of 12 and 18.
2 x 3 = 6
GCF(12, 18) = 6
18
Find the GCF of 12 and 16
4 is the GCF of 12 and 16
Factors of 12
212
26
33
1
Factors of 16
216
28
24
22
1


Factors of 12 = 2 x 2 x 3
Factors of 16 = 2 x 2 x 2 x 2
Multiply all the common factors of 12 and 16.
2 x 2 = 4
GCF(12, 16) = 4
19
Find the GCF of 6 and 9
3 is the GCF of 6 and 9
Factors of 6
26
33
1
Factors of 9
39
33
1


Factors of 6 = 2 x 3
Factors of 9 = 3 x 3
Multiply all the common factors of 6 and 9.
3 = 3
GCF(6, 9) = 3
20
Find the GCF of 24 and 36
12 is the GCF of 24 and 36
Factors of 24
224
212
26
33
1
Factors of 36
236
218
39
33
1


Factors of 24 = 2 x 2 x 2 x 3
Factors of 36 = 2 x 2 x 3 x 3
Multiply all the common factors of 24 and 36.
2 x 2 x 3 = 12
GCF(24, 36) = 12

Find Greatest Common Factor (GCF) Worksheets

Find the GCF of two numbers worksheet with answers to practice & learn 6th grade math problems on greatest common factor is available online for free in printable & downloadable (pdf & image) format. Tap on PRINT, PDF or IMAGE button to print or download this grade-6 worksheet to practice how to find the GCF by using prime factorization.

How to Use this Worksheet

In this sixth grade math worksheet, students are required to find the HCF (Highest or Greatest Common factor) of two given numbers by using prime factorization. To find the prime factors of a number, use special division method as like as the step by step work given in the answer key. The product of common prime factors of two given numbers is the Greatest Common Factor.

Answers Key

Teachers, parents or students can check or validate the solved math workbook of 6th grade math questions on writing HCF of 2 given numbers by using the corresponding answers key which comprises the step by step work for each problem in the worksheet.

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