extract_numbers.txt

let
    Source = Excel.CurrentWorkbook(){[Name="Table1"]}[Content],
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Mix", type text}}),
    #"Added Custom" = Table.AddColumn(
#"Changed Type", 
"Custom", 
each Text.Combine(List.RemoveNulls(List.Transform(Text.ToList([Name]),
each if Value.Is(Value.FromText(_), type number) then _ else null))))
in
    #"Added Custom"