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Highest Common Factor – HCF

Highest common factor (HCF) of two or more number is the greatest number which divides each of them exactly.


H.C.F of 18, 24 and 36 is as 6 is the greatest number which divides each of 18,24 and 36 exactly.

Methods of finding Highest common factor (HCF)

Common Factors Method

1. Find all the factors of each given number.

2. Find common factors of the given number.

3. The greatest of all the factors obtained in step 2, is the required H.C.F.

Prime Factors Method

1. Break each even numbers into its prime factors.

2. Find the product of all the prime factors common to all the numbers to get the required H.C.F.

Division Method

1. Divide the greater number by the smaller number.

2. By the remainder of division in step 1, divide the smaller number.

3. By the remainder in step 2, divide the remainder of step 1.

4. Continue in the same way, till to remainder is left. The last divisor is the required H.C.F.

Find the H.C.F of four number by division method

1. Find the H.C.F of any three given numbers by the previous method.

2. Then find the H.C.F of the fourth given number and the H.C.F obtained in step1. In the same way, the H.C.F for the five or more than five given numbers can be obtained.

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