EDIT: I cleaned up my answer a little bit, should be a bit more readable. You just need to break up your string and concatenate it with the returned value.
jQuery(document).ready(function() {
var $parent = jQuery(parent.document); // cache this so jquery doesnt have to instantiate the same object twice
var theFormID = $parent
.find('.theformclass')
.find('input[name="form_id"]').val();
var $form = $parent
.find("#abc_" + theFormId + "_number_103")
.fadeToggle("slow", "linear");
});
10
solved Passing returned jquery var to another jquery