This is a Challenge cache, in order to claim the you will need to find 25 Milticaches
A Multi-Cache ("multiple") involves two or more locations. The final location is a physical container. There are many variations, but most Multi-Caches have a hint to find the second cache, and the second cache has a hint to the third, and so on. An offset cache (where you go to a location and get hints to the actual cache) is considered a Multi-Cache.
Multis are awesome caches that take us to amazing places, while making us break a sweat finding all of its stages; they are my favorite type of caches as my first 3 finds ever were multis.
To find the right answer for this cache, you will need to use your math skills