Quote:
Originally Posted by boffking
What percentage of numbers are prime?
You can't take a percent of infinity.

Actually this calculation is the idea behind the Prime Number Theorem.
https://en.wikipedia.org/wiki/Prime_number_theorem
And to a first approximation the number of primes less than x is asymptotically x/ln(x). This means that the fraction of numbers that are prime goes to zero in the limit, but it does so in a well defined way.