title: How to increment differently based on a variable
body: <p>What I need to achieve is to increase room numbers.
  For example:</p>
  
  <blockquote>
    <p>101, 102, 103 for floor = 1;<br>
     201, 202, 203 for floor = 2 ;<br>
    and so on. </p>
  </blockquote>
  
  <p>How do I achieve this?</p>