gcd(x,y,...)
i1 : gcd(12,8,48) o1 = 4
i2 : R = QQ[x,y,z];
i3 : gcd(x^2*y,x*y^3^6) o3 = x*y o3 : R
i4 : gcd(x^36-1,x^24-1) 12 o4 = x - 1 o4 : R
The object gcd is an associative binary method function.