Nth Prime

Write a program that can tell you what the nth prime is.

By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that
the 6th prime is 13.

If your language provides methods in the standard library to deal with prime
numbers, pretend it doesn't exist and implement it yourself.

For installation and learning resources, refer to the
exercism help page.

For running the tests provided, you will need the Minitest gem. Open a
terminal window and run the following command to install minitest:

gem install minitest

If you would like color output, you can require 'minitest/pride' in
the test file, or note the alternative instruction, below, for running
the test file.

In order to run the test, you can run the test file from the exercise
directory. For example, if the test suite is called
hello_world_test.rb, you can run the following command:

ruby hello_world_test.rb

To include color from the command line:

ruby -rminitest/pride hello_world_test.rb

The test files may have the execution bit set so you may also be able to
run it like this:

./hello_world_test.rb

Source

A variation on Problem 7 at Project Euler view source