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Greatest Common Factor (GCF)

Find the highest common factor of the given numbers

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Greatest Common Factor


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Greatest Common Factor: 6


What is GCF?

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  • Greatest Common Factor

    Greatest Common Factor of any group of numbers is defined as the largest number that will be the factor of all the numbers in a group. Also called as Greatest Common Divisor or Highest Common Factor

    A factor is the number which divides another number without leaving a remainder. for eg: 2 , 3 , 4 , 6 are the factors of 12.

  • What Methods are there to find GCF (GCD/HCF)?

    • Division Method
    • Prime Factorization Method
    • Grid Method
    • Cake Method (Ladder Method)
    • Box Method
    • Listing factors Method

Division Method to find GCF

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  • Step 1: Divide the greatest number by the smallest number from the given set of numbers

  • Step 2: Now the remainder of above will be treated as divisor and divisor will be treated as dividend.

  • Step 3: Divide the first divisor by first remainder.

  • Step 4: Divide the second divisor(i.e first remainder) by second remainder.

  • Step 5: Proceed with these steps untill you get remainder 0.

  • Step 6: The last Divisor which leaves remainder as 0 is the GCF or HCF of the given numbers.

Examples: GCF of 12 and 30 using Division method.

  • Step 1: Divide 30 by 12.This leads to the remainder 6.

  • Step 2: Now divide 12 by 6.This gives remainder 0.

  • Step 3: So the GCF is 6.

  • Division Flow

    gcf-division-method

Prime Factorization method

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  • Step 1: Write down the prime factorization of each number

  • Step 2: Now take all the common factors of the numbers.

  • Step 3: Multiplication of the common factors will be the gcf of the numbers.

  • Example: GCF of 12 and 24 using Prime factorization method.

    Prime factorization of 12 = 2 x 2 x 3,
    Prime factorization of 24 = 2 x 2 x 2 x 3
    we have 2 , 2 and 3 as common factor take these factors. Leave other factors since they are not Common
    Multiply 2 x 2 x 3 this will be the gcf of 12 and 24.

    gcf-prime-factorization-method

Grid Method

  • Step 1: Write down the number seperated by vertical line and horizontal line to seperate each grid.

  • Step 2: Divide the numbers by prime number(should exactly divide all the numbers) and write the result in the next row grid.

  • Step 3: Continue dividing the numbers till the last common factor.Product of the prime numbers in the left side grid will be the gcf of the numbers.

Cake / Ladder Method

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  • Step 1: This method is the one of the easiest way to find the gcf of the numbers. Write down the number in the first layer.(layer looks like top of the cake |__|.)

  • Step 2: Divide the Layer numbers by prime numbers which divides the numbers and leave 0 as the remainder .Write the result in the next Layer.

  • Step 3: Continue dividing the cake layers till the last common factor.GCF is the product of the prime numbers in the left side of the layers.

  • Example: GCF of 15 and 27

    gcf-cake-method

Box Method

  • Step 1: Write down the number seperated by vertical line and horizontal line.

  • Step 2: Divide the numbers by common factors and write the result in the next line.

  • Step 3: Continue dividing the numbers by till the last common factors.Product of the common factors will be the GCF of the numbers.

Listing factors Method

  • Step 1: List all the factors of each numbers seperately.

  • Step 2: Collect the common factors of all numbers.

  • Step 3: Product of all common factors will be the greatest common factor(GCF).This is also known as Greatest Common divisor or Highest Common Factor.

Table of GCF / HCF of Most Common Numbers

Conversion Table Icon

GCF Input

HCF Input

GCF / GCD / HCF Output

gcf of 12 and 18

hcf of 12 and 18

6

gcf of 8 and 12

hcf of 8 and 12

4

gcf of 16 and 24

hcf of 16 and 24

8

gcf of 24 and 36

hcf of 24 and 36

12

gcf of 18 and 24

hcf of 18 and 24

6

gcf of 12 and 16

hcf of 12 and 16

4

gcf of 12 and 20

hcf of 12 and 20

4

gcf of 24 and 40

hcf of 24 and 40

8

gcf of 24 and 32

hcf of 24 and 32

8

gcf of 36 and 48

hcf of 36 and 48

12

gcf of 32 and 48

hcf of 32 and 48

16

gcf of 27 and 36

hcf of 27 and 36

9

gcf of 30 and 45

hcf of 30 and 45

15

gcf of 6 and 8

hcf of 6 and 8

2

gcf of 12 and 30

hcf of 12 and 30

6

gcf of 16 and 28

hcf of 16 and 28

4

gcf of 18 and 27

hcf of 18 and 27

9

gcf of 36 and 54

hcf of 36 and 54

18

gcf of 28 and 42

hcf of 28 and 42

14

gcf of 15 and 20

hcf of 15 and 20

5

gcf of 16 and 20

hcf of 16 and 20

4

gcf of 24 and 30

hcf of 24 and 30

6

gcf of 6 and 9

hcf of 6 and 9

3

gcf of 6 and 15

hcf of 6 and 15

3

gcf of 4 and 12

hcf of 4 and 12

4

gcf of 36 and 60

hcf of 36 and 60

12

gcf of 15 and 10

hcf of 15 and 10

5

gcf of 9 and 15

hcf of 9 and 15

3

gcf of 45 and 60

hcf of 45 and 60

15

gcf of 8 and 10

hcf of 8 and 10

2

gcf of 24 and 60

hcf of 24 and 60

12

gcf of 9 and 18

hcf of 9 and 18

9

gcf of 30 and 15

hcf of 30 and 15

15

gcf of 12 and 15

hcf of 12 and 15

3

gcf of 6 and 12

hcf of 6 and 12

6

gcf of 48 and 72

hcf of 48 and 72

24

gcf of 14 and 28

hcf of 14 and 28

14

gcf of 8 and 16

hcf of 8 and 16

8

gcf of 6 and 18

hcf of 6 and 18

6

gcf of 27 and 45

hcf of 27 and 45

9

gcf of 18 and 42

hcf of 18 and 42

6

gcf of 4 and 10

hcf of 4 and 10

2

gcf of 6 and 10

hcf of 6 and 10

2

gcf of 48 and 18

hcf of 48 and 18

6

gcf of 20 and 24

hcf of 20 and 24

4

gcf of 15 and 45

hcf of 15 and 45

15

gcf of 30 and 42

hcf of 30 and 42

6

gcf of 32 and 40

hcf of 32 and 40

8

gcf of 24 and 72

hcf of 24 and 72

24

gcf of 8 and 24

hcf of 8 and 24

8

gcf of 36 and 42

hcf of 36 and 42

6

gcf of 4 and 6

hcf of 4 and 6

2

gcf of 5 and 10

hcf of 5 and 10

5

gcf of 12 and 28

hcf of 12 and 28

4

gcf of 10 and 25

hcf of 10 and 25

5

gcf of 60 and 72

hcf of 60 and 72

12

gcf of 24 and 42

hcf of 24 and 42

6

gcf of 30 and 75

hcf of 30 and 75

15

gcf of 42 and 56

hcf of 42 and 56

14

gcf of 12 and 30

hcf of 12 and 30

6

gcf of 72 and 90

hcf of 72 and 90

18

gcf of 16 and 48

hcf of 16 and 48

16

gcf of 14 and 42

hcf of 14 and 42

14

gcf of 24 and 28

hcf of 24 and 28

4

gcf of 9 and 36

hcf of 9 and 36

9

gcf of 6 and 24

hcf of 6 and 24

6

gcf of 20 and 32

hcf of 20 and 32

4

gcf of 48 and 30

hcf of 48 and 30

6

gcf of 32 and 8

hcf of 32 and 8

8

gcf of 54 and 72

hcf of 54 and 72

18

gcf of 24 and 48

hcf of 24 and 48

24

gcf of 10 and 20

hcf of 10 and 20

10

gcf of 3 and 6

hcf of 3 and 6

3

gcf of 45 and 81

hcf of 45 and 81

9

gcf of 7 and 14

hcf of 7 and 14

7

gcf of 24 and 54

hcf of 24 and 54

6

gcf of 16 and 18

hcf of 16 and 18

2

gcf of 2 and 8

hcf of 2 and 8

2

gcf of 15 and 24

hcf of 15 and 24

3

gcf of 10 and 45

hcf of 10 and 45

5

gcf of 32 and 80

hcf of 32 and 80

16

gcf of 8 and 15

hcf of 8 and 15

1

gcf of 12 and 21

hcf of 12 and 21

3

gcf of 8 and 20

hcf of 8 and 20

4

gcf of 20 and 16

hcf of 20 and 16

4

gcf of 45 and 30

hcf of 45 and 30

15

gcf of 40 and 60

hcf of 40 and 60

20

gcf of 48 and 56

hcf of 48 and 56

8

gcf of 3 and 12

hcf of 3 and 12

3

gcf of 20 and 40

hcf of 20 and 40

20

gcf of 30 and 50

hcf of 30 and 50

10

gcf of 7 and 21

hcf of 7 and 21

7

gcf of 20 and 30

hcf of 20 and 30

10

gcf of 36 and 63

hcf of 36 and 63

9

gcf of 18 and 21

hcf of 18 and 21

3

gcf of 3 and 8

hcf of 3 and 8

1

gcf of 28 and 12

hcf of 28 and 12

4

gcf of 12 and 42

hcf of 12 and 42

6

gcf of 40 and 64

hcf of 40 and 64

8

gcf of 60 and 90

hcf of 60 and 90

30

gcf of 10 and 35

hcf of 10 and 35

5

gcf of 42 and 70

hcf of 42 and 70

14

gcf of 5 and 6

hcf of 5 and 6

1

gcf of 18 and 72

hcf of 18 and 72

18

gcf of 15 and 12

hcf of 15 and 12

3

gcf of 16 and 64

hcf of 16 and 64

16

gcf of 3 and 18

hcf of 3 and 18

3

gcf of 6 and 16

hcf of 6 and 16

2

gcf of 63 and 84

hcf of 63 and 84

21

gcf of 49 and 98

hcf of 49 and 98

49

gcf of 36 and 90

hcf of 36 and 90

18

gcf of 13 and 26

hcf of 13 and 26

13

gcf of 25 and 75

hcf of 25 and 75

25

gcf of 9 and 21

hcf of 9 and 21

3

gcf of 14 and 16

hcf of 14 and 16

2

gcf of 4 and 16

hcf of 4 and 16

4

gcf of 10 and 14

hcf of 10 and 14

2

gcf of 5 and 7

hcf of 5 and 7

1

gcf of 25 and 45

hcf of 25 and 45

5

gcf of 75 and 90

hcf of 75 and 90

15

gcf of 4 and 8

hcf of 4 and 8

4

gcf of 18 and 32

hcf of 18 and 32

2

gcf of 6 and 30

hcf of 6 and 30

6

Frequently Asked Questions on GCF.

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  • Greatest common factor of any group of numbers is defined as the largest number that will be the factor of all the numbers in a group.

  • There are various mehtods to find HCF/GCF.Lets discuss how to find the hcf using listing factors method.First we need to list all the factors of each number separately and collect the common factors. Product of these common factors will be the HCF.

  • GCF facttoring is just taking out the common polynomial from the higher degree polynomials, which will make the problem to get solved easily.

  • GCF - G for Greatest , C for Common and F for Factor. GCF is Greatest Common Factor of the the given group of numbers. HCF - H for Highest, C for Common and F for Factor

  • Greatest Common Factor of 12 and 18 is 6.

  • Least common multiple of 8 and 12 is 4.

  • Greatest Common Factor of 16 and 24 is 8.

  • Greatest Common Factor of 24 and 36 is 12.

  • Greatest Common Factor of 12 and 16 is 4.

  • Greatest Common Factor is 4.

  • Greatest Common Factor of 24 and 40 is 8.

  • GCF of 24 and 32 is 8.

  • GCF of 36 and 48 is 12.

  • GCF of 32 and 48 is 16.

  • GCF of 27 and 36 is 9.

  • GCF of 30 and 45 is 15.

  • GCF of 6 and 8 is 2.

  • GCF of 12 and 30 is 6.