Detecting prime numbers in Ruby

prime.rb

# A prime is a natural number greater than 1 that cannot be formed by multiplying two smaller natural numbers
def prime?(int)
  # A prime is a natural number greater than 1...
  return false if int < 2

  # Is _int_ evenly divisible by any number 2 -> int-1?
  (2..(int - 1)).each do |divisor|
    return false if int % divisor == 0
  end
  return true
end

(1..100).each do |int|
  puts int if prime?(int)
end

# OR, using the standard Prime class

require "prime"

(1..100).each do |int|
  puts int if Prime.prime?(int)
end