PHP - เรื่องการคำนวนคับ ทำยังไงถึงมันถึงจะคำนวณตามลูปอะคับ

<table class="table table-bordered">
                	<tr>
                    	<td colspan="6">Method-1 : Male</td>
                    </tr>
                    <tr>
                        <td width="5%"> ลำดับ</td><td width="50%">รายการสินค้า</td><td width="10%">ราคา</td><td width="10%">จำนวน</td><td width="15%">ยอดรวม</td><td width="10%">Action</td>
                    </tr>
                    	<SCRIPT Language="JavaScript">

function startCalc(){ 
interval = setInterval("calc()",1); 
} 
function calc(){ 
num = document.autoSumForm.num.value; 
price = document.autoSumForm.price.value; 

document.autoSumForm.sum_price.value = (num) * (price); 
} 
function stopCalc(){ 
clearInterval(interval); 
} 
</SCRIPT>
                    <?php  
				
							$qr_x =dbQuery("SELECT * FROM tbl_product where sex_status = 'x' ORDER BY product_name ASC");	
							$row =@mysql_num_rows($qr_x);
							 $i=0;
							while ($i<$row){
							$rs_x=mysql_fetch_array($qr_x);
							$product_id = $rs_x['product_id'];
							$product_name = $rs_x['product_name'];
							$price = $rs_x['price'];
							
				?>   
                     <tr>
                        <td width="5%"><? echo $i+1;?></td><td width="50%"><? echo $product_name;?></td><td width="10%"><? echo $price;?><input type="hidden" name="price"  value="<? echo $price;?>" size="2" onfocus="startCalc()" onblur="stopCalc()"></td><td width="10%"><input type="text"  name="num" size="2" onfocus="startCalc()" onblur="stopCalc()" ></td><td width="15%"><input type="text" name="sum_price"  class="input-label" size="2" onfocus="startCalc()" onblur="stopCalc()" disabled="disabled"></td><td width="10%">Action</td>
                    </tr>
                    <?
					$i++;
							}
					?>
                </table>