As so far I've memorized Pi to 240 decimal places purely by rote memorization. However recently I've read a book that detailed mind palaces and PAO (Person-Action-Object) visualization, which should aid greatly if practiced. I could start easily with a base 10 system for each position (IE 109 is transformed to some person who represents 1, doing some action that represents 0 to some object that represents 9), but I'm thinking of taking some time and expanding it to base 100 (00-99), as that would make memorizing numbers twice (6 digits per image instead of 3) as fast with a greater variation in the numbers and images that would probably also help keeping them in my mind once the initial setting up my mnemonic system was done. I say this because I've seen that the USA PI record is only 15,000, now I got to 240 through pure rote memorization doing 5 minutes a day sometimes. If I actually put some work into it regularly I could probably pretty easily get to that stage. I'd need many mind palaces though, I'd have to travel the streets and buildings of Oxford much, and have some cohesive order, but I really could do it, I think it'd be a fun title to have even temporarily.