How do I use mod_rewrite to change example.com/1/2/3 to example.com/3 ??

If you define a rule per each string, yes. Because I can't see any pattern in your example to use a more flexible regular expression.

RewriteEngin on
# rewrit incomming request /3/ --> /1/2/3
Rewriterule ^3/$ /1/2/3/ [L]

are you planning to use that in a .htaccess file or in httpd.conf?

it should be
RewriteEngine on
(missing 'e')

woa thats confusing, don't think I can do this myself...

Well basically what I need the rule to be like will depend on what is clicked on...  (I have a web archiving website)...

So one link will be:

example.com/data/March-2006/20/thesitewillbehere/

which will be re-written as:

example.com/thesitewillbehere/

And the March-2006 and the 20 can change dynamically as well as the folder name for "thesitewillbehere", is this possible to do with a rule?

if you access example.com/data/March-2006/20/thesitewillbehere/ you can rewrite it to example.com/thesitewillbehere/ (so example.com/thesitewillbehere/ exists physically) the other way /data/March-2006/20/thesitewillbehere/ exists but you're calling /thesitewillbehere/ will not work. You must use a RewriteMap or a rule for each string in that case.

RewriteEngine on
# /data/March-2006/20/thesitewillbehere/ --> /thesitewillbehere/
RewriteRule ^data/[^/]+/[^/]+/([^/]+)/$ /$1/ [L]

Is it possible to have thesitewillbehere be the same???

In theory that directory is supposed to be the same each month this tool runs...  SO I guess I should try to make them different?

For example maybe doing like example.com/data/March-20-2006-thesitewillbehere which I can then re-write as example.com/March-20-2006-thesitewillbehere

These directories are created dynamically each month, so is it possible to auto-add a new rule everytime a directory is created?  Or is there a way to make this not necessary?

Wow dude thanks, I need to learn regular expressions it seems :)