Prime numbers from (n) to (2n)

[limitkiller]

is there any proofs for:
"for any natural (n) there are prime numbers from n to 2n,including" ??

 

[Gib Z]

This is known as "Bertrand's Postulate", and a long but elementary proof is contained here: http://en.wikipedia.org/wiki/Proof_of_Bertrand's_postulate

 

[limitkiller]

thanks
but i had trouble understanding last part :"This gives us the contradiction:n < 468."
could anyone help me with that

 

[limitkiller]

help...no one answered for a long time...