You can use index
and break
function:
{foreach from=$entries key=i item=topic name=foo}
{if $smarty.foreach.foo.index == 10}
{break}
{/if}
{if $topic.topic_style == question}
<li>
<a href="topic.php?id={$topic.id}">{$topic.title}</a>
</li>
{/if}
{/foreach}
Break function is described here:
Break in Smarty's / Dwoo's foreach
You could just use array_slice
:
{foreach $entries|@array_slice:0:10 as $topic}
...
{/foreach}