SSRS SQL 2008 R2 - How to reference the value of other groups?

Question

I have a matrix setup in the report designer in BIDS. Below is a screenshot:

All I want to do is use an expression to multiply the value of COL GROUP 1 by COL GROUP 2, for each ROW GROUP as illustrated in red. What would be the best way to achieve this?

EDIT: For clarity, each column group is filtered to only return a single value per adjacent column group

Answer 1

On a per row basis, you can use..

=ReportItems!ColGroup1Value.Value * ReportItems!ColGroup2Value.Value

This assumes that the textbox which contains the value for "ColGroup1Value" is named ColGroup1Value.

See https://learn.microsoft.com/en-us/sql/reporting-services/report-design/built-in-collections-reportitems-collection-references-report-builder for more information about ReportItems.