[NumLock]

Код:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    EditHex: TEdit;
    EditDec: TEdit;
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
  EditHex.Text:=IntToHex(1234567890123456789, 16);
  EditDec.Text:=IntToStr(StrToInt64('$'+EditHex.Text));
end;

end.