Which of the following numbers are co-prime


Question: Which of the following numbers are co prime? (a) 18 and 35 (b) 15 and 37 (c) 30 and 415 (d) 17 and 168 (e) 216 and 215 (f) 81 and 16

Answer: option a,b,d,e,f  are co prime numbers. 

Explanation:

Coprime numbers are numbers which has only 1 as their HCF.

(a) 18 and 35
18 and 35  have no common factors, Therefore 18 and 35 are coprime numbers. 

(b) 15 and 37 
As they have no common factors, 15 and 37 are co-prime numbers. 

(c) 30 and 415 
As they have a common factor - 5, hence 30 and 415  are not co-prime. 

(d) 17 and 168 
As they have no common factors, 17 and 168 are coprime numbers.  

(e) 216 and 215 
As they have no common factors, 216 and 215 are coprime numbers.  

(f) 81 and 16 
As they have no common factors, they are co prime numbers. 

 Thus, option a,b,d,e,f  are co prime numbers.