5. Which of the following numbers are co-prime?
(a) 18 and 35     (b) 15 and 37         (c) 30 and 415
(d) 17 and 68     (e) 216 and 215     (f) 81 and 16

Answers (1)

(a) 18 and 35 

Factors of 18=1,2,3,6,9,18

 Factors of 35=1,5,7,35 

Common factor =1 

Therefore, the given two numbers are co-prime.  

 

(b)15 and 37 

Factors of 15=1,3,5,15 

Factors of 37=1,37 

Common factors =1 

Therefore, the given two numbers are co-prime. 

 

(c) 30 and 415

Factors of 30=1,2,3,5,6,10,15,30 

Factors of 415=1,5,83,415 

Common factors =1,5 

As these numbers have a common factor other than 1, the given two numbers are non co-prime.  

 

(d) 17 and 68

Factors of 17=1,17

 Factors of 68=1,2,4,17,34,68 

Common factors =1,17 

 As these numbers have a common factor other than 1, the given two numbers are non co-prime.  

 

(e) 216 and 215

 Factors of 216=1,2,3,4,6,8,9,12,18,24,27,36,54,72,108,216

 Factors of 215=1,5,43,215 

Common factors =1

 Therefore, the given two numbers are co-prime.  

 

(f) 81 and 16

 Factors of 81=1,3,9,27,81 

Factors of 16=1,2,4,8,16 

Common factors =1

 Therefore, the given two numbers are co-prime

Exams
Articles
Questions