procedure TFACTURA.FormCreate(Sender: TObject);
begin
...
Memo4.OnChange:= MemoChange;
Memo7.OnChange:= MemoChange;
end;
procedure TFACTURA.MemoChange(Sender: TObject);
var
v1,v2: Double;
c: Integer;
begin
c:= 0;
Memo2.Lines.Clear;
while (c < Memo4.Lines.Count) and (c < Memo7.Lines.Count) do
begin
if TryStrToFloat(Memo4.Lines[c],v1) and TryStrToFloat(Memo7.Lines[c],v2) then
Memo2.Lines.Add(Format('%8.2f',[v1*v2]))
else
Memo2.Lines.Add('Error en operandos. (Línea' + IntToStr(c) +')');
Inc(c);
end;
end;
...