Scanf.scanf "%d" (fun t ->
    for i = 1 to t do
        Scanf.scanf " %s" (fun s ->
            let calc n k =
                Array.init (n - 1) (fun i ->
                    let q = k.(i) + k.(i + 1) in
                    if q >= 10 then (q mod 10) + 1 else q)
            in
            let rec loop r s =
                if r = 1 then Printf.printf "%d\n" s.(0) else
                    loop (r - 1) (calc r s)
            in
            let n = String.length s in
            loop n (Array.init n (fun i -> int_of_char s.[i] - 48))
        )
    done
)