How can I add a number to the Total, not only the value

I am having a bit of an issue, clients are ordering but it is hard to follow how many products they have been choosing. How can I add a total of the quantity of the products they have been choosing.

It's the total number of products selected regardless of the quantity of each product, right? 

You can do this with calculation and count() function.

https://www.jotform.com/help/259-How-to-Perform-Form-Calculation-Using-a-Widget

Here's the formula:

There's an offset of 1, so I subtract it instead to get the correct total of products selected.

Here's a demo: https://www.jotform.com/201407291911044.