Here's the procedure I use and the resulting problem I'm having in ArcGIS 10.1.
First I use the Add XY coordinates tool to add POINT_X and POINT_Y fields to the attribute table of a point layer. I then add a new text field so that I can concatenate the XY values using the field calculator and the following query: [POINT_X] & "," & [POINT_Y]. For some reason, most of the entries in the concatenated field go to many more decimal places than I want.
For example: POINT_X = -97.831771, POINT_Y = 29.782709, and the concatenated field (XY) = -97.8317708001,29.7827091999. I just want the XY field to equal -97.831771,29.782709! What is causing this error? Somehow I've been able to work around this problem occasionally but I can never reproduce it when I want to.