A method of connection with the divine.
A Germanic-based divination system, the runes derive from the Germanic alphabet that dates back to about 50 AD (tracing it earlier is very difficult and possibly bad scholarship). We have no direct and obvious reason to believe that Runes were used for divination at any point, though some can point to the Voluspa for a single passage of interest, while others can point to Tacitus for an explicit statement of "casting lots" that are carved. Of course, that doesn't stop them from working as a medium of communication with the divine. In general, the Elder Futhark is used in divination, and the symbol set is one that would be readily understood by the Germanic deities. Each letter represents a word, and there are poems that also give meanings. Numerology, when connected with Runes, is bunk; I have yet to see any convincing evidence otherwise.