decided to have a go at using the case statement. Why won't this work?

-------------------------------------------------------------------------------------
def double_it
  print "Please enter a whole number (or type 'h' for help) : "
  num = gets.chomp
  case num
    when num == 'h'
      puts
      puts "A whole number is 45 for example, or 12564."
      puts
    when num.to_i > 1
      num * num
      print num.to_s
    when num.to_i <= 0
      puts "The number must be positive!"
  end
end
double_it
gets
--------------------------------------------------------------------------------------