title: Ruby: no implicit conversion of fixnum into string
body: <p>Trying to solve one of the problems in Chris Pine's book. Asks users to input their first and last names, then it should display the total number of characters of both.</p>
  
  <p>Here's one of many solutions I've come up with:</p>
  
  <pre><code>puts "First name?"
  first_name = gets.chomp
  
  puts "Last name?"
  last_name = gets.chomp
  
  total = first_name.length.to_i + last_name.length.to_i
  
  puts 'Did you know you have ' + total + ' characters in your name ' + first_name + last_name + '?'
  </code></pre>