title: Return a growing number based on another number in javascript
body: <p>I want to make a function taking one number argument that returns:</p>
  
  <ul>
  <li><code>4</code> for <code>0.1</code></li>
  <li><code>8</code> for <code>1</code></li>
  <li>etc... it should return a valid number following that pattern no matter what number is passed, though the number is typically expected to be a float between <code>0</code> and <code>1</code></li>
  </ul>
  
  <p>I don't know the proper term to call this kind of operation.
  I can only come up with a function like <code>num =&gt; 4 + 4 * num</code>, but that is incorrect since passing <code>0.1</code> returns <code>4.4</code>.</p>