Can you please attach a sample workbook(.twbx) so that we can suggest you according to your dataset. Also, please elaborate your requirement as I am still not getting you that why you need to create a calculated measure for achieving this?
Hi Arthur, you might want to look at creating sets that way the Top 10 are identified automatically. Add the set to color shelf to create the color for Top 10 and the rest.
Good luck! Let us know if you have further questions