List of prime numbers using Array methods

Question

I have a code to get list of prime numbers:

def primes_numbers num
    primes = [2]

    3.step(Math.sqrt(num) + 1, 2) do |i|
        is_prime = true     

          


        

Answer 1

You can list prime numbers like this as well.

Example Array: ar = (2..30).to_a
ar.select{ |n| (2..n).count{ |d| (n % d).zero? } == 1 }