As you could probably guess by the title, this cache is the 500th we have hidden or adopted! Amazingly, our very first geocache hide was on these same trails, and once you solve the puzzle, may very well walk right by it on the way to this one. We honestly didn't even realize we had hidden so many until someone pointed it out at a recent event and asked if we had something special planned for hide #500. Since 500 hides is a feat that few geocachers have achieved (at least not around here!), something a little different had to be created.
It really has been a pleasure placing all of these caches over the years in the area. From the long hikes to the grandma approved series, to even a few paddles, it's really been a blast! Speaking of grandma approved, grandma has been a big part in helping with the hides. While she didn't do any of the work, she was present in the car when countless caches were hidden, and always enjoys going out for rides while they are being maintained.
The container you seek is a pretty typical lock-and-lock container, but with a twist. Inside the container are 500 trade items. Yes, that's right, 500! Granted they are pretty small as you will tell, but hey, there were exactly 500 in there when this was hidden! Also inside are a log book and pencil, with room for more trade items if you'd like to leave anything.
So where is the cache? This is a puzzle after all! Well, some simple addition will get you there, and you've already gotten enough information to figure out what to add. Good luck! 
PLEASE REHIDE THE CACHE EXTREMELY WELL!!! Make sure it's far "under" its hiding spot and out of sight from the path. Thanks, hope you enjoy, and thanks for finding our caches over the years. It's been a pleasure reading all the logs!
You can validate your puzzle solution with certitude.