Limit the number of registrations

I have a "class" where people can pick from multiple available dates. There are 12 seats available for each class and people can register one or multiple people for a class. Is there any way to limit the number of submissions on a form based on a quantity drop-down in the form (number of people they are registering)? So far all I've been able to figure out is how to limit a form itself to 12 submissions. That won't work because someone could register more than just themselves even though that's only "one" submission.

We have a few different widgets that allow for limiting the quantity available for options. 

Here is a link to our inventory widgets:

http://widgets.jotform.com/widget/inventory 

http://widgets.jotform.com/widget/quantity_gift_registry 

http://widgets.jotform.com/widget/gift_registry

All of those allow for setting a quantity available.  Once the quantity reaches 0, the option is disabled.

Thank you! The quantity gift registry widget worked perfect!