title: How do you complete the following Regex
body: <p>I am looking for a regex expression that will accept the following: The capital letter A followed by any number of digits.  This might also be a decimal number. All of these are valid: A1, A500, A543.987</p>
  
  <p>This is NOT OK to accept: Apple, AE100</p>
  
  <p>Currently I have <code>[A]\w.[0-9]*</code> but it accepts <code>App</code> and <code>AE100</code>.</p>