Check if the number is prime in Ruby

prime.rb

# trial division — the simplest primality test

def is_prime(number)
  return number > 1 if number <= 3
  return false if number % 2 == 0 || number % 3 == 0

  i = 5
  while i * i <= number do
    return false if number % i == 0 || number % (i + 2) == 0
    i = i + 6
  end
  true
end