Hello Doug Lott,
Sorry for the late response. Unfortunately RadNumericUpDown does not support such a built - in functionality. We will provide our customers with such (SelectAll(), Select(int start, int length)) methods in the forthcoming SP1. It will be launched in a couple of weeks.
All the best,
the Telerik team
Check out Telerik Trainer
, the state of the art learning tool for Telerik products.