title: How to make this regex allow spaces c#
body: <p>I have a phone number field with the following regex:</p>
  
  <pre><code>[RegularExpression(@"^[0-9]{10,10}$")]
  </code></pre>
  
  <p>This checks input is exactly 10 numeric characters, how should I change this regex to allow spaces to make all the following examples validate</p>
  
  <pre><code>1234567890
  12 34567890
  123 456 7890
  </code></pre>
  
  <p>cheers!</p>