Question

In each of the following examples, write all the factors of the numbers and find the greatest common divisor.

i. 28, 42 

ii. 51, 27 

iii. 25, 15, 35

Answer 1

i. Factors of 28 = 1,2,4, 7, 14, 28 

Factors of 42 = 1,2, 3, 6, 7, 14, 21, 42 

∴ HCF of 28 and 42 = 14 

ii. Factors of 51 = 1, 3, 17, 51 

Factors of 27 = 1, 3, 9, 27 

∴ HCF of 51 and 27 = 3 

iii. Factors of 25 = 1, 5, 25 

Factors of 15 = 1, 3, 5, 15 

Factors of 35 = 1, 5, 7, 35 

∴ HCF of 25, 15 and 35 = 5