Хочу разобраться все же

<?if(!defined("B_PROLOG_INCLUDED") || B_PROLOG_INCLUDED!==true)die();?>
<div class="catalog-section">
<?if($arParams["DISPLAY_TOP_PAGER"]):?>
<p><?=$arResult["NAV_STRING"]?></p>
<?endif?>

<!—ИСПОЛНЯЮЩИЙ СКРИПТ—-->

<script>
function cost(){
var cost_p=document.getElementById('cost_p').innerHTML;
var amount_p=document.getElementById('amount_p').value;
document.getElementById('cost_out').innerHTML=cost_p*amount_p;
}
</script>

<!————————-->
<hr noshade color="indigo"></hr>
<table class="data-table" cellspacing="0" cellpadding="0" border="0" width="100%">
<thead>
<tr>
<td><b><?=GetMessage("CATALOG_TITLE")?></b><
/td>
<?if(count($arResult["ITEMS"]) > 0):
foreach($arResult["ITEMS"][0]["DISPLAY_PROPERTIES"
] as $arProperty):?>
<td><?=$arProperty["NAME"]?></td>
<?endforeach;
endif;?>
<?foreach($arResult["PRICES"] as $code=>$arPrice):?>
<td><b><?=$arPrice["TITLE"]?></b><
/td>
<?endforeach?>
<?if(count($arResult["PRICES"]) > 0):?>


<?endif?>
<td><b>Количество</b></td>
<td><b>Сумма</b></td>
</tr>
</thead>
<?foreach($arResult["ITEMS"] as $arElement):?>
<?
$this->AddEditAction($arElement['ID'], $arElement['EDIT_LINK'], CIBlock::GetArrayByID($arParams["IBLOCK_ID"], "ELEMENT_EDIT"));
$this->AddDeleteAction($arElement['ID'], $arElement['DELETE_LINK'], CIBlock::GetArrayByID($arParams["IBLOCK_ID"], "ELEMENT_DELETE"), array("CONFIRM" => GetMessage('CT_BCS_ELEMENT_DELETE_CONFIRM')));
?>
<tr id="<?=$this->GetEditAreaId($arElement['ID']
);?>">
<td>
<a href="<?=$arElement["DETAIL_PAGE_URL"]?>">
<?=$arElement["NAME"]?></a>
<?if(count($arElement["SECTION"]["PATH"]
)>0):?>

<?foreach($arElement["SECTION"]["PATH"]
as $arPath):?>
/<a href="<?=$arPath["SECTION_PAGE_URL"]?>">
<?=$arPath["NAME"]?></a>
<?endforeach?>
<?endif?>
</td>
<?foreach($arElement["DISPLAY_PROPERTIES"] as $pid=>$arProperty):?>
<td>
<?if(is_array($arProperty["DISPLAY_VALUE"]))
echo implode("&nbsp;/&nbsp;", $arProperty["DISPLAY_VALUE"]);
elseif($arProperty["DISPLAY_VALUE"] === false)
echo "&nbsp;";
else
echo $arProperty["DISPLAY_VALUE"];?>
</td>
<?endforeach?>
<?foreach($arResult["PRICES"] as $code=>$arPrice):?>
<td>
<?if($arPrice = $arElement["PRICES"][$code]):?>
<?if($arPrice["DISCOUNT_VALUE"] < $arPrice["VALUE"]):?>
<s><?=$arPrice["PRINT_VALUE"]?></s><br /><span class="catalog-price"><?=$arPrice["PRINT_DISCOUNT_VALUE"
]?></span>
<?else:?>

<!———ОПРЕДЕЛЯЕМ ПЕРЕМЕННУЮ ЦЕНЫ———->
<div id="cost_p" class="catalog-price"><?=$arPrice["DISCOUNT_VALUE"
]?></div>
<!———————————————->



<?endif?>
<?else:?>
&nbsp;
<?endif;?>
</td>

<?endforeach;?>
<?if(count($arResult["PRICES"]) > 0):?>

<td>
<!—————ПОЛЕ ДЛЯ ВВОДА КОЛИЧЕСТВА————>

<input onkeyup=cost(); id=amount_p style='text-align:right;border:1px solid #999999' type="text" name="kolvo" value="0" size="1">

<!—————————————————->
</td>
<td>

<!—————--ЗДЕСЬ ВЫВОДИМ СУММУ—————->
<div id=cost_out>0</div>
<!—————————————————->
</td>
<td>




</td>

<?endif;?>
</tr>
<?endforeach;?>
</table>
<hr noshade color="indigo"></hr>
<noindex>
<?if($arElement["CAN_BUY"]):?>
<a href="<?echo $arElement["ADD_URL"]?>" rel="nofollow"><?echo GetMessage("CATALOG_ADD")?></a>
<?elseif((count($arResult["PRICES"]) > 0) || is_array($arElement["PRICE_MATRIX"])):?>
<?=GetMessage("CATALOG_NOT_AVAILABLE")?>
<?endif?>


&nbsp;
</noindex>
<?if($arParams["DISPLAY_BOTTOM_PAGER"]):?>
<p><?=$arResult["NAV_STRING"]?></p>
<?endif?>
</div>