Wow... nice one ppl i didn`t think of that, but... maybe he is trying to say that in one shop to display the items in pages ...  
like he said, a shop with 100 items having more pages so the frame won`t need to scrool down so much (25 items per page from the same shop) 
I`m not so good at this but you could try something like this: 
  
$pages=(int) ($items/25)+1; 
if($items % 25 == 0) 
{ 
$pages--; 
} 
for($i=1;$i <= $pages;$i++) 
{ 
$stl=($i-1)*35; 
print "<font color=green>Page: </font><font color=green>$i</font> 
"; 
} 
print " 
"; 
$q=$db->query("SELECT .... ORDER BY $by $ord LIMIT $st,25"); 
$no1=$st+1; 
$no2=$st+25;  
...