<form id="metematix" name="metematix" method="post" action="<?php echo $_SERVER['PHP_SELF']; ?>">
  <table width="200" border="1">
    <tr>
      <td width="80">Sayı 1 </td>
      <td width="104">
        <input name="s1" type="text" id="s1" size="9" maxlength="9" />
      </td>
    </tr>
    <tr>
      <td>Sayı 2 </td>
      <td><input name="s2" type="text" id="s2" size="9" maxlength="9" /></td>
    </tr>
    <tr>
      <td>İşlem : </td>
      <td>
        <select name="islem" id="islem">
          <option value="+">Topla</option>
          <option value="*">Çarp</option>
          <option value="/">Böl</option>
          <option value="-">Çıkar</option>
        </select>
      </td>
    </tr>
    <tr>
      <td>Gönder : </td>
      <td>
        <input type="submit" name="Submit" value="Ok'le" />
        <input name="hesapla" type="hidden" id="hesapla" value="evet" />
      </td>
    </tr>
  </table></form>
  <?php 
error_reporting(E_ALL ^ E_NOTICE); 
if ((isset($_POST["hesapla"])) && ($_POST["hesapla"] == "evet")) { 
switch($_POST['islem']) { 
case"+": $sonuc = $_POST['s1']+$_POST['s2']; break; 
case"*": $sonuc = $_POST['s1']*$_POST['s2']; break; 
case"/": $sonuc = $_POST['s1']/$_POST['s2']; break; 
case"-": $sonuc = $_POST['s1']-$_POST['s2']; break; 
default: $sonuc = "İşlem Sonucu Bilinmiyor. Daha Doğrusu Senin Ne Yaptığın Bilinmiyor :D";
} echo "<strong>Sonuc :</strong> $sonuc"; }?>