function AddXY(Const AXValue, AYValue: Double; Const AXLabel: String; AColor: TColor) : Longint;

  for i := 0 to 10 do
  begin
    Chart1.Series[0].AddXY(i,i*2,'Text',clRed);
  end;

Form1.StringGrid1.Cells[8,1]

for k:=1 to 10 do
Chart1.Series[0].AddXY(k,StrToFloat(Form1.StringGrid1.Cells[8,1]),' ',clREd);

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, TeEngine, Series, StdCtrls, ExtCtrls, TeeProcs, Chart, Grids;

type
  TForm1 = class(TForm)
    StringGrid1: TStringGrid;
    Chart1: TChart;
    Button1: TButton;
    Series1: TLineSeries;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var
   k : Integer;
begin
for k := 1 to 7 do
  Chart1.Series[0].AddXY(k,StrToFloat(Form1.StringGrid1.Cells[k,1]),' ',clREd);
end;

end.

for i := 1 to StringGrid1.RowCount-1 do
   begin
      bez := 0;
          bez := bez + StrToInt(StringGrid1.Cells[7,i]); // это я так понимаю сумма элементов нужного столбца
     Chart1.Series[0].AddXY(i,bez,'',clRed);
  end;

bez := bez + StrToFloat(StringGrid1.Cells[7,i]);

   Chart1.Series[0].Clear;
   bez := 0;
   for j := 1 to StringGrid1.RowCount-1 do
      begin
         bez := bez + StrToFloat(StringGrid1.Cells[7,j]);//подсчитываем сумму элементов
      end;
   Chart1.Series[0].AddXY(1,bez,' ',clRed);//Выводим один столбец с суммой

for j := 1 to StringGrid1.RowCount-1 do
begin
    bez := bez + StrToFloat(
      StringReplace(
        StringReplace(StringGrid1.Cells[7, j], '.', DecimalSeparator, [rfReplaceAll]),
        ',', DecimalSeparator, [rfReplaceAll]
      ) // подсчитываем сумму элементов

    ); // Независимо от того, точка или запятая стоит в StringGrid
end;

Project Project1.exe raised exeption Class EconvertError With Message "' is not a valid Floating value Process stoped
.Use Step or run to continue

Form6.Show;

procedure Create

var
 Bez:Real;
 j:integer;
begin
 Chart1.Visible := true;
 Chart1.Series[0].Clear;
   bez := 0;
   for j := 1 to Form1.StringGrid1.RowCount-1 do
      begin
         if not(Length(Form1.StringGrid1.Cells[7,j]) = 0) then //Если ячейка не пуста
         bez := bez + StrToFloat(Form1.StringGrid1.Cells[7,j]);//подсчитываем сумму элементов
      end;
   Chart1.Series[0].AddXY(1,bez,' ',clRed);//Выводим один столбец с суммой

stoimost:integer

procedure TForm2.LabeledEdit3KeyPress(Sender: TObject; var Key: Char);
var
  Not_DESIMAL : string;
begin
  if DecimalSeparator = ',' then
  Not_DESIMAL := '.'
 else
  Not_DESIMAL := ',';

  if Key = Not_DESIMAL then
  Key := DecimalSeparator;
 if ((Key in ['0' .. '9']))OR(Key = DecimalSeparator) then begin
  if (Key = DecimalSeparator) AND (Pos(DecimalSeparator,(Sender AS TLabeledEdit).Text) > 0) then begin
   Key := Chr(0);
  end;
 end else if (Key=Chr(VK_RETURN))OR (Key=Chr(VK_BACK)) then begin

 end
 else Key := Chr(0);
end;

begin
  if not(Key in ['0' .. '9']) then begin
     Key := Chr(0);
  end;
 end else if (Key=Chr(VK_RETURN))OR (Key=Chr(VK_BACK)) then begin
 end
 else Key := Chr(0);
end;