Formula for prime numbers?

[quadell]

A friend of mine needs to know a formula, given n, that will return an upper bound on the number of prime numbers less than or equal to n. I told him f(n) = n, but he didn't laugh. I think he wants the lowest upper bound anyone can come up with. Does anyone know a good formula for this?

Your Quadell

[Arnold Winkelried]

http://mathworld.wolfram.com/PrimeNumberTheorem.html

[Gilligan]

I have a proof of the Riemann Hypothesis, but the margins of this thread are too narrow to contain it...

[Arnold Winkelried]

That's OK Gilligan, will you offer me $100,000 to recreate your proof?

[Louie]

What's sad is that I laughed at Gilligan's joke. :(

[quadell]

Wow! Thanks much.

Your Quadell