when playing with PowerPivot and adding ∑Values you get the prefix Sum(…) before the value.
1.Click on the dropdown combo on the right hand.
2. Click on Edit Measure.
3.Copy the Formula in the “Measure will use this formula” …
4.Click on the New Measure icon in the Power Pivot Ribbon
5.paste the formula to the measure settings and change the measure name.
6. That’s it. now you have a new calculated member with your own caption ( Alias or what ever)