title: Regex matching numbers and decimals
body: <p>I need a regex expression that will match the following:</p>
  
  <pre><code>.5
  0.5
  1.5
  1234
  </code></pre>
  
  <p>but NOT</p>
  
  <pre><code>0.5.5
  absnd (any letter character or space)
  </code></pre>
  
  <p>I have this that satisfies all but <code>0.5.5</code></p>
  
  <pre><code>^[.?\d]+$
  </code></pre>