$amount_of_keys = keys %upload;

# for all instances of $amount_of_keys % 20 {
# print qq(<a href="url#.html></a>);
# if there is a remainder that isn't % 20 {
# print qq(<a href="url#.html></a>); }  }



##</code><code>##

keys 1-20  would print url1.html
keys 21-40 would print url2.html
keys 41-60 would print url3.html
keys 61-80 would print url4.html (even though we don't have 80 images, we have a surplus and still need to generate a url for it).