In PowerPoint even though you can use Category or Series names as Data Labels, most of the time users tend to use Values as Data Labels. Values are typically numbers, and there are many ways in which you can format these Data Labels. You may want to do so for several reasons such as limiting or expanding the number of decimal digits shown, or to show a currency symbol along with the values, or even to show the value in percentage etc. Do note that these format changes can be made both within Excel and PowerPoint — in this tutorial, we explore how you do so in Excel at the data level (all data for PowerPoint charts resides in Excel).
Learn how to format numbers used as Chart Data Labels using Excel in PowerPoint 2011 for Mac.

