let
    calcNeed = (subTable) => 
    let
        setOrder = Table.Sort(Table.Distinct(subTable, {"Date"}), {"Date"}),
        items = List.Buffer(Table.ToRecords(setOrder)),
        itemCount = List.Count(items),
        generate = List.Generate(
            () => [i = 0, rec = items{i}, value = rec[Base]],
            each [i] < itemCount,
            each [i = [i] + 1, rec = items{i}, value = [value] * (1 - rec[Churn]) + rec[Sales]],
            each [[rec], [value]]
        ),
        toTable = Table.FromRecords(generate),
        expandRecords = Table.ExpandRecordColumn(toTable, "rec", Table.ColumnNames(subTable))
    in
        expandRecords,
    Source = Excel.CurrentWorkbook(){[Name="Data"]}[Content],
    typed = Table.TransformColumnTypes(Source,{{"Serv", type text}, {"Type", type text}, {"Base", type number}, {"Date", type date}, {"Sales", type number}, {"Churn", type number}}),
    calc = Table.Group(typed, {"Serv", "Type"}, {"temp", calcNeed}),
    result = Table.ExpandTableColumn(calc[[temp]], "temp", Table.ColumnNames(typed) & {"value"}),
    #"Changed Type" = Table.TransformColumnTypes(result,{{"Serv", type text}, {"Type", type text}, {"Base", type number}, {"Sales", type number}, {"Churn", type number}, {"value", type number}, {"Date", type date}})
in
    #"Changed Type"