title: How do I validate an Australian Medicare number?
body: <p>I'm developing an online form in which user-entered Medicare numbers will need to be validated.</p>
  
  <p>(My specific problem concerns Australian Medicare numbers, but I'm happy for answers regarding American ones too. This question is about Medicare numbers in general.)</p>
  
  <p>So how should I do it?</p>
  
  <p>(It would be good to have the answer in Javascript or a regex.)</p>