use the modulus operator -- % isn't just for hashes.

for (1..100) {
    print "$_ ";
    print "\n" if ($_ % 5 ==0); # add a break (or other string) every 
+5 elements 
}
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There are other ways to do it, but that's the most perl, I think.
Other ways?

@foo = map {$_*5} (1..10); # generate a list by fives.
print join " ", @foo,"\n\n"; # see the fives.


print "<table>"; # replace with calls to CGI.pm as appropriate.
for my $ctr (0..$#foo) {
    print "  <tr>\n   ";
    print " <td>$_</td>" for (($ctr*5)+1 .. $foo[$ctr]);
    print "\n  </tr>\n";
}
print "</table>\n\n";
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