gcd

let the gcd be d.
d divides n as well as n+1.
also divides their difference i.e 1
hence if d|1 then d must be 1.

thank you

gcd=hcf[1]

ooh kk silly of me!!!!!!

gcd(n,1)=1
by bezout's theorum,
nu+1*v=1
or,nu+v+nv-nv=1
or,(n+1)*v + n(u-v)=1.

now ,
v and (u-v) are integers
so, gcd(n+1,n)=1.

hope that helps ..................