The Memory Palace technique is a good one. It's very similar to an astral temple. There's another technique that is identical to the astral temple but I don't remember the name. These are for great deals of information. For numbers there are other techniques. Look into NLP.
Mannaz:#20. Rune of logic and the left side of the brain. Used for enhancing intellect and strengthening the memory. Helps one to gain more knowledge of one’s self which is essential in working magick. Amethyst