ingresa = gets.chomp
               ingresa = ingresa.downcase
   if ingresa !="sum"||ingresa !="sub"||ingresa !="mul"||ingresa !="div"
          puts"You didn't type [Sum,Sub,Mul,Div]"
          puts"Try again."
   end

Hi to everyone, I'm a newbie with ruby and I don't know what I doing
wrong with my code, i want to make a simple calculator just for training
so what I want to do is to make sure that the user receives a message
that he didn't type sum, sub, mul or div to start the calculator, the
other part is finished and working but I don't know how to solve this,
could you help me with this issue and explain me a little my mistake.
thank you!

-- 
Posted via http://www.ruby-forum.com/.