Question

Using Euclid's division algorithm, find whether the pair of numbers $231,396$ are coprime or not.

Answer 1

$\Rightarrow 396=1\times 231+165$

$\Rightarrow 231=1\times 165+66$

$\Rightarrow 165=2\times 66+33$

$\Rightarrow 66=2\times 33+0$

∴ The $HCF$ of $231,396$ is $33$ not $1$, so they are not co-prime.