title: Regex - Group string with space
body: <p>I need to group a string into groups of 3 characters.</p>
  <p>Examples:</p>
  <pre><code>In: 900123456 -&gt; Out: 900 123 456
  In: 90012345  -&gt; Out: 900 123 45
  In: 90012     -&gt; Out: 900 12
  </code></pre>
  <p>Is there any way to do this with regex?</p>
  <p>Thank you very much.</p>