I used the techniques described on this page to memorize pi. I've got 60 memorized where I can recall the digits by place. For example, the 40th decimal place is 1. In the table, it's the last digit of column A10. The phrase in A10 is ToP CaT, which translates to 1971, and the last 1 is the 40th digit.
https://www.ludism.org/mentat/PiMemorisation