# CLASS-4H.C.F - COMMON FACTOR METHOD OR LISTING METHOD

FINDING HIGHEST COMMON FACTOR (H.C.F) -

Common Factor Method Or Listing Method -

We know that the factors of a number are exact divisors of that number.

The HIGHEST COMMON FACTOF (H.C.F) of two or more numbers is the largest number that divides the given numbers without a remainder in each case.

For example, in a set of numbers 14, 21 and 28 we can easily say all these numbers are divisible by 7. So, the highest factor that can divide all three numbers without a remainder is 7. The HCF is 7.

1. COMMON FACTOR METHOD OR LISTING METHOD :-

In this method,

§ STEP 1.) First we find the factors of the given numbers separately.

§ STEP 2.) Then we underline the common factors of the numbers and write it down.

§ STEP 3.) We find the greatest common factor amongst the common factors.

§ STEP 4.) The greatest common factor is the H.C.F of the given numbers.

SOLVED EXAMPLE:-

Find the H.C.F of 24, 36 and 48 using the listing method (common factor method). SOLUTION :-

24                    36                    48

24 ÷ 1 = 24            36 ÷ 1 = 36            48 ÷ 1 = 48

24 ÷ 2 = 12            36 ÷ 2 = 18            48 ÷ 2 = 24

24 ÷ 3 = 8             36 ÷ 3 = 12            48 ÷ 3 = 16

24 ÷ 4 = 6             36 ÷ 4 = 9              48 ÷ 4 = 12

36 ÷ 6 = 6              48 ÷ 6 = 8

STEP 1.)

Factors of 24 are 1, 2, 3, 4, 6, 8, 12, 24

(RED COLOR ALL THE COMMON FACTORS)

Factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18, 36

Factors of 48 are 1, 2, 3, 4, 6, 8, 12, 16, 24, 48

STEP 2.)

Common factors are 1, 2, 3, 4, 6, 12

STEP 3.)

The H.C.F is 12

STEP 4.)

Answer : The H.C.F of 24, 36 and 48 is 12.