Forum:Can my wikia subtract two numbers?

I run the Trackers Interface Wiki and my goal is to reach 100 pages by Christmas. I already know how to do a countdown, but I want to do something like:

Our goal is to reach 100 pages by Christmas, which leaves us (countdown code) to make pages!

to make something like this:

Our goal is to reach 100 pages by Christmas, which leaves us 24 days 0 hours 55 minutes 30 seconds to make 39 pages!

(Note: countdown timer would be running, but you have to configure the wiki and I don't have permission)
 * should work, but will be heavily cached --  Random Time  21:14, December 1, 2011 (UTC)
 * I think it's counting all pages and templates and categories, because it's coming out that we have 460 pages. I adjusted the code a bit for just regular content articles:

. Thanks, Iggyvolz 23:33, December 1, 2011 (UTC)