Highest Common Factor



Highest common factor (H.C.F) of two or more numbers is the greatest number which divides each of them exactly.


Now we will learn about the method of finding highest common factor (H.C.F).

Steps 1:

Find all the factors of each given number.


Step 2:

Find common factors of the given number.


Step 3:

The greatest of all the factors obtained in Step 2, is the required highest common factor (H.C.F).


For Example:

1. Find the highest common factor (H.C.F) of 6 and 9.


Factors of 6 = 1, 2, 3 and 6.

Factors of 9 = 1, 3 and 9.

Therefore, common factor of 6 and 9 = 1 and 3.

Highest common factor (H.C.F) of 6 and 9 = 3.

Therefore, 3 is H.C.F. or G.C.D. greatest common divisor of 6 and 9.

H.C.F. or G.C.D. of given numbers is the greatest number which divides all the numbers without leaving a remainder.



2. Find the highest common factor (H.C.F) of 14 and 18.

Factors of 14 = 1, 2, 7 and 14.

Factors of 18 = 1, 2, 3, 6, 9 and 18.

Therefore, common factor of 14 and 18 = 1 and 2.

Highest common factor (H.C.F) of 14 and 18 = 2.




3. Find the highest common factor (H.C.F) of 15 and 10.

Factors of 15 = 1, 3, 5 and 15.

Factors of 10 = 1, 2, 5 and 10.

Therefore, common factor of 15 and 10 = 1 and 5.

Highest common factor (H.C.F) of 15 and 10 = 5.


4. Find the highest common factor (H.C.F) of 12 and 18.

Factors of 12 = 1, 2, 3, 4, 6 and 12.

Factors of 18 = 1, 2, 3, 6, 9 and 18.

Therefore, common factor of 12 and 18 = 1, 2, 3 and 6.

Highest common factor (H.C.F) of 12 and 18 = 6 [since 6 is the highest common factor].


5. Find the highest common factor (H.C.F) of 24 and 36.


Factors of 24 = 1, 2, 3, 4, 6, 8, 12 and 24.

Factors of 36 = 1, 2, 3, 4, 6, 9, 12, 18 and 36.

Therefore, common factor of 24 and 36 = 1, 2, 3, 4, 6, 8 and 12.

Highest common factor (H.C.F) of 24 and 36 = 12.



● Factors.

 Common Factors.

 Prime Factor.

● Repeated Prime Factors.

● Highest Common Factor (H.C.F).

● Examples on Highest Common Factor (H.C.F).

 Greatest Common Factor (G.C.F).

 Examples of Greatest Common Factor (G.C.F).

 Prime Factorisation.

 To find Highest Common Factor by using Prime Factorization Method.

 Examples to find Highest Common Factor by using Prime Factorization Method.

 To find Highest Common Factor by using Division Method.

 Examples to find Highest Common Factor of two numbers by using Division Method.

 To find the Highest Common Factor of three numbers by using Division Method.







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