Question

show that the number 231 and 396 are not co primes 

Answer 1

Co-Prime numbers are numbers which has no common factor except the number one(1) i.e., their H.C.F. is 1 only.

Factors of 231 = 3×11×7×1
Factors of 396 = 3×3×11×2×2×1

Here, The common factors (H.C.F.) is 1, 3 & 11.

Hence, the two nos. 231 & 396 are not co-prime numbers.

Answer 2

231  It is easy to see that 3 is a factor of that as sum of digits is divisible by 3
396 is also divisible by 3 - same principle

so they are not co prime, as 3 is a common factor.

Answer 3

The numbers are said to be co prime, if they do not have a common factor other than 1.
Factors of 231 are=1,3,7,11................231.
Factors of 396 are=1,2,3,11.................396.
Here common factors are 1,3 and 11.
Therefore the numbers 231 and 396 are not Co- Prime  numbers.
Hope it helps!