title: Regular expression to validate multiple ranges of numbers
body: <p>I am trying to validate numbers which are allowed to belong to multiple ranges. e.g.:</p>
  
  <p><strong><em>A number x is valid if it lies between 150-200, or 700-750</em></strong></p>
  
  <p>Basically I want to store these restrictions in a database, so I thought storing them as regexes would be a nice way of handling this problem. </p>
  
  <p>I am new to regular expressions, so am not being able to come up with one for the above validation.</p>