title: Ruby on Rails, realtime calc
body: <p>im learning RoR atm and im trying to code a calculator webapp.
  The thing is: I want that the operations are gettin calculated in realtime.
  So if i type in 2+2 the calc says 4 without that i pressed some "CALC NOW" button.</p>
  
  <p>Can someone give me some hints how i could to that? Do i need to learn AJAX for that?</p>