Count distinct running total

See my article on Mean Time Between Failure (MTBF) which uses EARLIER: http://community.powerbi.com/t5/Community-Blog/Mean-Time-Between-Failure-MTBF-and-Power-BI/ba-p/339586

Hi DrewCarousel , 

You could refer to Greg_Deckler ' s suggestions to use DAX to achieve this goal, or you also could use M code like below to achieve this goal

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMjDUByIjAyMDJR0lR0dDBUNHR6VYHaCEEUUSTk5GCkZOTuToiAUA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type text) meta [Serialized.Text = true]) in type table [Date = _t, Postcode = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Date", type date}, {"Postcode", type text}}),
    #"Grouped Rows" = Table.Group(#"Changed Type", {"Postcode", "Date"}, {{"all", each _, type table [Date=date, Postcode=text]}}),
    #"Added Custom" = Table.AddColumn(#"Grouped Rows", "Custom", each Table.AddIndexColumn([all], "a",1,1)),
    #"Expanded Custom" = Table.ExpandTableColumn(#"Added Custom", "Custom", {"a"}, {"a"}),
    #"Removed Columns" = Table.RemoveColumns(#"Expanded Custom",{"all"})
in
    #"Removed Columns"

Best Regards,
Zoe Zhi

If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.