Find the common factors of:
(a) 20 and 28
(b) 15 and 25
(c) 35 and 50
(d) 56 and 120

To do :

We have to find the common factors of the given pairs of numbers.

Solution :

(a) Factors of 20 are 

$20 = 1\times 20$

$= 2\times 10$

$= 4\times 5$

Therefore, factors of 20 are 1,2,4,5,10 and 20.

Factors of 28 are

$28 = 1\times 28$

$= 2\times 14$

$= 4\times 7$

Therefore, factors of 28 are 1,2,4,7,14 and 28.

The common factors of 20 and 28 are 1,2 and 4.

(b) Factors of 15 are 

$15 = 1\times 15$

$= 3\times 5$

$= 15\times 1$

Therefore, factors of 15 are 1,3,5 and 15.

Factors of 25 are

$25 = 1\times 25$

$= 5\times 5$

$= 25\times 1$

Therefore, factors of 25 are 1,5 and 25.

The common factors of 15 and 25 are 1 and 5.

(c) Factors of 35 are 

$35 = 1\times 35$

$= 5\times 7$

$= 35\times 1$

Therefore, factors of 35 are 1,5,7 and 35.

Factors of 50 are

$50 = 1\times 50$

$= 2\times 25$

$= 5\times 10$

$= 10\times 5$

$= 50\times 1$

Therefore, factors of 50 are 1,2,5,10,25 and 50.

The common factors of 35 and 50 are 1 and 5.

(d) Factors of 56 are 

$56 = 1\times 56$

$= 2\times 28$

$= 4\times 14$

$=7\times8$

$=56\times1$

Therefore, factors of 56 are 1,2,4,7,8,14,28 and 56.

Factors of 120 are

$120 = 1\times 120$

$= 2\times 60$

$= 3\times 40$

$= 4\times 30$

$= 5\times 24$

$= 6\times 20$

$= 8\times 15$

$= 10\times 12$

$= 120\times 1$

Therefore, factors of 120 are 1,2,3,4,5,6,8,10,12,15,20,24,30,40,60 and 120.

The common factors of 56 and 120 are 1,2,4 and 8.

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Updated on: 10-Oct-2022

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