You have to bind to the Value
property of the control. It is of type double. For more info you can check the First Look example of our demos : http://demos.telerik.com/wpf/?NumericUpDown/FirstLook
Let me know if you have more questions.
the Telerik team
Registration for Q1 2011 What’s New Webinar Week is now open. Mark your calendar for the week starting March 21st and book your seat
for a walk through all the exciting stuff we ship with the new release!