Hello Ramki,
Thank you for your post. I have been looking through it and I created a sample project for you. Basically I used the XamNumericEditor’s ValueToDisplayTextConverter property to convert the value if it is -999.999 to “N.A”. NB! this is only the display value, when not in edit mode. The original value remains Double type and is -999.999. Please note, we are making efforts to ensure all posts are addressed by an Infragistics expert. We believe that the other community members could benefit from this thread as well.
Feel free to write me if you need further assistance.