title: Exclude certain numbers from range of numbers using Regular expression
body: <p>Could some one help me with the regular expression, where we can exclude certain numbers in between from a range of numbers. </p>
  
  <p>Presently, <code>^([1-9][0][0-9])$</code> is the regular expression that is configured. Now if i want to exclude a few numbers/one number(<code>501</code>,<code>504</code>) from it, then how would the regular expression look/be.</p>