Could use some help :)

[Stoltenborg]

I want customers to be able to buy each product in a quantity of 2, 4, n, n+2 ...

Let's say I have 10 tickets. I want customers to be able to buy each product in quantities of 2, 4, 6, n+2, then if there is only 1 ticket or one ticket left, they can buy the quantity of 1. Do you get what I am saying?

how can this be done?


here is the file, I could use some simple help...

<FORM name="orderform_{$product.productid}_{$product.add_date}" method=post action="cart.php?mode=add">
<input type=hidden name=productid value="{$product.productid}">
<input type=hidden name=cat value="{$smarty.get.cat|escape:"html"}">
<input type=hidden name=page value="{$smarty.get.page|escape:"html"}">
<tr>
{if $product.distribution eq ""}
<td height=25 width=15% nowrap>{$lng.lbl_quantity}
</td>
<td width=20%>
{if $config.General.unlimited_products ne "Y" and ($product.avail le 0 or $product.avail lt $product.min_amount)}
<b>{$lng.txt_out_of_stock}</b>
{else}
{if $config.General.unlimited_products eq "Y"}
{math equation="x+1" assign="mq" x=$config.Appearance.max_select_quantity}
{else}
{math equation="x/y" x=$config.Appearance.max_select_quantity y=$product.min_amount assign="tmp"} 
{if $tmp<2}
{assign var="minamount" value=$product.min_amount} 
{else} 
{assign var="minamount" value=0}
{/if} 
{math equation="min(maxquantity+minamount, productquantity)+1" assign="mq" maxquantity=$config.Appearance.max_select_quantity minamount=$minamount productquantity=$product.avail}
{/if}
<select name=amount>
{if $product.min_amount le 1}
{assign var="start_quantity" value=1}
{else}
{assign var="start_quantity" value=$product.min_amount}
{/if}
{section name=quantity loop=$mq start=$start_quantity}
<option value="{%quantity.index%}" {if $smarty.get.quantity eq %quantity.index%}selected{/if}>{%quantity.index%}</option>
{/section}
</select>