RPN Calculator

rpn_calc.rb

class Rpn
  def evaluate(expression)
    operators = ['+', '-', '*']
    stack = []
    symbols = expression.split(' ')

    symbols.each do |symbol|
      if operators.include?(symbol) 
        number_two = stack.pop
        number_one = stack.pop

        stack.push(number_one.send(symbol, number_two))
      else
        stack.push(symbol.to_i)
      end
    end
    p stack.pop
  end
end