Return result when keyup pressed

Question

I am trying to return a result from an input for later use

var banknote_5 = $("#note_5").keyup(function() {
  var banknote_5 = $(this).val();
  result = $("#result_note_5").text(banknote_5 * 5).toString();
  return result;
})

console.log(banknote_5);

What I want to do is each time the user enter a number, I want to return it so I can calculate the total for each notes and coin.

For some reason I cannot return the result, there is nothing.