How do I find position of a mouse click inside a div?

How do I find position of a mouse click inside a div?

I can find how much a DIV has scrolled using "scrollTop()".  But it turns out I need to know more than that.  I need to know what exact vertical position in my div the user clicked on. 

My div has a fixed height and there is too much content to show, so the user has to scroll down to see all the content.

So suppose he has scrolled 3 pages down in the Div and then, he clicks 160 pixels down within the div. So I would add 160 to scrollTop(), but I have one question:

1. How do I get that "160".  Is there a jquery call that will give it to me?

Thanks,

Gideon