How do I generate the first n prime numbers?

Question

I am learning Ruby and doing some math stuff. One of the things I want to do is generate prime numbers.

I want to generate the first ten prime numbers and the first ten

Answer 1

class Numeric
  def prime?
    return self == 2 if self % 2 == 0

    (3..Math.sqrt(self)).step(2) do |x|
      return false if self % x == 0
    end

    true
  end
end

With this, now 3.prime? returns true, and 6.prime? returns false.

Without going to the efforts to implement the sieve algorithm, time can still be saved quickly by only verifying divisibility until the square root, and skipping the odd numbers. Then, iterate through the numbers, checking for primeness.

Remember: human time > machine time.