title: Function that takes a number and returns another number and vice versa
body: <p>I recently came across a question in an interview and am stumped at how to solve it. I would really appreciate any assistance.</p>
  
  <p>The question asked me to create a function that received a number as a parameter (599) and returns a different number, but will also work in reverse. The issue is that I was not permitted to use any sort of conditional operator e.g. <code>if</code>, <code>switch</code> etc...</p>
  
  <p>This was as far as I got:</p>
  
  <pre><code>function changeValue(v) {
    // return 599 if 395 passed and vice versa
  }
  </code></pre>