title: grouping checkboxes and allow checking a maximum of three in each group
body: <p>I would like to have an application where a user will enter data for arbitrary individuals. each individual will have a choice of a maximum of three of six options. I want help on how to force a maximum of three choices using jquery on any indivual.</p>
  
  <p>here is a sample code</p>
  
  <pre><code>&lt;div id="subscriber_1"&gt;
     &lt;input type=checkbox name=national&gt;
     &lt;input type=checkbox name=international&gt;
     &lt;input type=checkbox name=business&gt;
     &lt;input type=checkbox name=entertainment&gt;
     &lt;input type=checkbox name=religion&gt;
     &lt;input type=checkbox name=sports&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>the subscribers can run upto 20, like subscriber_1, subscriber_2, ... subscriber_20. I will be grateful for your assistance.</p>