Referencing Cells in Power Query

You can use the List.Generate function to accomplish the same result.

I started off with just your In Process and Scrap Qty columns.

And I stored the first "Initial Qty" value of 86 as a Parameter named Initial since you said you got that from someplace else.

Then, with this code:

let
    Source = Excel.CurrentWorkbook(){[Name="Table1"]}[Content],
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"In Process", Int64.Type}, {"Scrap Qty", Int64.Type}}),
    #"Initial/Finished" = List.Generate(
        ()=>[i=Initial, f=Initial - #"Changed Type"[In Process]{0} - #"Changed Type"[Scrap Qty]{0}, idx=0],
        each [idx] < Table.RowCount(#"Changed Type"),
        each [i=[f], f = [f]-#"Changed Type"[In Process]{[idx]+1} - #"Changed Type"[Scrap Qty]{[idx]+1}, idx=[idx]+1 ],
        each {[i],[f]}),
    
    #"Add Initial/Finished" = Table.FromColumns(
        Table.ToColumns(#"Changed Type") &
        {List.Transform(#"Initial/Finished", each _{0})} &
        {List.Transform(#"Initial/Finished", each _{1})},
        type table[In Process=Int64.Type, Scrap Qty=Int64.Type,Initial Qty=Int64.Type, Finish Qty=Int64.Type]),
    #"Reordered Columns" = Table.ReorderColumns(#"Add Initial/Finished",{"Initial Qty", "In Process", "Finish Qty", "Scrap Qty"})

in  
    #"Reordered Columns"

you obtain this result:

Hi Oadr21 ,

ronrsnfld lbendlin Thanks for your concern about this case!
And Oadr21 another solution:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMjJQ0lEyUIrViVZCsIyALEMwyxAhaIGi0BBNCy4x/CxjLGKmaOYZmxBjYCwA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [#"In Process" = _t, #"Scrap Qty" = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"In Process", Int64.Type}, {"Scrap Qty", Int64.Type}}),
    #"Added Index" = Table.AddIndexColumn(#"Changed Type", "Index", 1, 1, Int64.Type),
    #"Added Custom" = Table.AddColumn(#"Added Index", "Initial Qty", each let 
currentIndex = [Index]
in
if [Index] = 1 then 86 else 86 - List.Sum(
    Table.SelectRows(#"Added Index", each [Index] <= currentIndex)[In Process]) - List.Sum(
        Table.SelectRows(#"Added Index", each [Index] <= currentIndex)[Scrap Qty]
    )),
    #"Added Custom1" = Table.AddColumn(#"Added Custom", "Finish Qty", each let 
   currentIndex = [Index],
   nextRow = Table.SelectRows(#"Added Custom", each [Index] = currentIndex +1)
in
   if Table.IsEmpty(nextRow) then 0 else Record.Field(nextRow{0}, "Initial Qty"))
in
    #"Added Custom1"

Output:

Best Regards,
Dino Tao
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