WPF Telerik RadGridView: Need Formula based column

I am using Telerik's RadGridView to display some data.

When data in one column changes, I want to change the data in another column based on a simple formula. For example: When data in Age column 开发者_如何学运维is edited, I want to change the other column's (Premium) value as Premium = (Age * 1.2)

Handling CellEditEnded or RowEditEnded doesn't help at all. Any ideas?

You need our expression column: http://demos.telerik.com/wpf/?GridView/ExpressionColumn