[SOLVED] Add Sequential ID To Each Widget

I want to add an individual sequentially numbered ID to each widget. In the template code, I have no problem adding the div with ID. However, I don't know how WP calls out a sequential variable. I can't seem to find any clear documentation on this.

For example, if you have three widgets in the sidebar, the source HTML will show:

<div id="widgetcontainer1">...content...</div>
<div id="widgetcontainer2">...content...</div>
<div id="widgetcontainer3">...content...</div>

I have no problem assigning a generic <div id="widgetcontainer"> in the template but I'm not sure how to add the automatic sequential numbering. I have some widgets that call out some messy class assignments, so this will help me simplify for a particular project.