Possible Duplicate:
Why is $\gcd(a,b)=\gcd(b,r)$ when $a = qb + r$?
Any idea how to prove that if $a,b \in \Bbb Z$ with $b = aq + r$, then $\gcd(a,b) = \gcd(a,r)$?
Possible Duplicate:
Why is $\gcd(a,b)=\gcd(b,r)$ when $a = qb + r$?
Any idea how to prove that if $a,b \in \Bbb Z$ with $b = aq + r$, then $\gcd(a,b) = \gcd(a,r)$?