=try <operation> otherwise <alternate result> (например, null)

let
    Sourse = Excel.CurrentWorkbook(){[Name="Таблица1"]}[Content],
    Add = Table.AddColumn(Sourse , "Объем_", each if [Column1] = "Группа1" then [Column2] else null),
    Split = Table.SplitColumn(Add, "Объем_", Splitter.SplitTextByEachDelimiter({" "}, QuoteStyle.Csv, true), {"Объем.1", "Объем"}),
    Transform = Table.TransformColumns(Split,{{"Объем", each Text.Trim (_, {"(", ")" , "а".."я", "А".."Я", "ё", "+", "-", "/", " "}), type text}}),
    Types = Table.TransformColumnTypes(Transform,{{"Объем", type number}}),
    Remove = Table.RemoveColumns(Types,{"Объем.1"})
in
    Remove

let
    from = Excel.CurrentWorkbook(){[Name="Таблица1"]}[Content],
    fn=(t)=> [  a = Text.AfterDelimiter(Text.From(t, "ru-RU"), " ", {0, RelativePosition.FromEnd}),
                b = Text.ToList(a),
                c = List.Select(b, each List.ContainsAny({_},{"0".."9"}&{","})),
                d = Number.From(Text.Combine(c))][d],
    add = Table.AddColumn(from, "Объем", each if [Column1] = "Группа1" then fn([Column2]) else null)
in
    add

Text.Select( "text", {".","0".."9"})

// Таблица1
let
    Sourse = Excel.CurrentWorkbook(){[Name="Таблица1"]}[Content],
    #"Added Custom" = Table.AddColumn(Sourse, "Пользовательская", each [
    a=Text.Split(_[Column2]," "), c={"0".."9"},
    b=List.Transform(a, each Text.PositionOfAny(_, c)),d=Table.FromColumns({a,b}),
    e=List.Last(Table.SelectRows(d, each [Column2] >= 0)[Column1]),
    f=Number.From(Text.Remove(e, {"(", ")" , "а".."я", "А".."Я",";", "_"}))][f] )
in
    #"Added Custom"

let
    Sourse = Excel.CurrentWorkbook(){[Name="Таблица1"]}[Content],
    LastNum = Table.AddColumn(Sourse, "LastNum", each 
        [a=Text.ToBinary(Text.From([Column2]),0),
         b=List.RemoveLastN(Binary.ToList(a),(_)=>not((_>47 and _<58) or _=44)),
         c=#binary(List.LastN(b,(_)=>(_>47 and _<58) or _=44)),
         d=Number.From(Text.FromBinary(c))][d], 
        type number
    )
in
    LastNum