Hi Harry,
Thanks for your interest in Syncfusion products.
You can use the Format property of StyleInfo Class to format the numbers in GridDataBoundGrid. Below is the code snippet:
this.gridDataBoundGrid1.Binder.InternalColumns[0].StyleInfo.Format = "#,###.##";
Here is the minimal sample that illustrates the same:
http://websamples.syncfusion.com/samples/Grid.Windows/Grid_WF_GDBGNumberFormat_F72057/main.htm Please let me know if it helps.
Regards,
Subhasheela R