Zitat:
function tform1.prim(zahl:integer):boolean;
var i:integer;
begin
result:=true;
for i := 2 to round(sqrt(zahl)) do
if zahl mod i=0 then
result:=false;
end;

procedure TForm1.Button1Click(Sender: TObject);
var i:integer;
begin
ListBox1.Clear;
for i:=StrToInt(Edit1.Text) to StrToInt(Edit2.Text) do
if prim(i)=true then
ListBox1.Items.Add(IntToStr(i));
Form1.Caption:=IntToStr(ListBox1.Items.Count);
end;