Prime Number Collector

Lets calculate 1,2,3,5,7,11,13,17,.. Calculating prime numbers still interested for some people until now. Particulary with computer more very very faster to find biggest prime numbers. This application challange you to how long you can patient to wait your computer work. You can download the software

How is it work?
To test what a number is prime using with repeated division with from 2 until that number less by one. To detect it just see remain of division result from one of a lot of division operstion. If just one have zero as remain, it's mean not a prime. We can test a number using with Mod operator, perhaps with repeating calculation.
procedure TForm1.Button1Click(Sender: TObject); var cukp, i, j, maks: cardinal; prima: boolean; begin if Edit1.Text = '' then Exit; Stopped:= false; Button3.Enabled:= false; ListBox1.Clear; maks:= StrToInt(Edit1.Text); for i:=2 to Maks do begin Application.ProcessMessages; if Stopped = true then begin Button3.Enabled:= true; exit; end; Cukp:= i; j:= 2; repeat if (i mod j) = 0 then //this is not a prime number begin j:= cukp; prima:= false; end else begin j:= j + 1; prima:= true; end; if i in[2,3,7,11,13] then //this is a prime number begin prima:= true; j:= cukp; end; until j = cukp; if prima then begin ListBox1.Items.Add(IntToStr(i)); end; end; Stopped:= true; Button3.Enabled:= true; ShowMessage('Done.'+#13+ 'Found '+ IntToStr(ListBox1.Count)+ ' Prime Number(s)'); end;
Okay, you can get the source code here.