Have you tried connecting memories with story-telling in your head? I have aphantasia too. I once did a little experiment to memorize the digits of numbers, which is really hard for me. Even 6 digits is very hard. What I did was I made up words for each number from 0 to 9 0 .. frog 1 .. house 2 .. garden This is just a random example of words to illustrate what I am doing.. you can find better words yourself I am sure. I believe the more extraordinary the words, the easier to remember in your story. Example: 0 .. talking frog 1 .. burning house 2 .. blue garden Then you start connecting the numbers into a story that you invent on the fly while reading the number. There was once a talking frog that lived in a blue garden. That blue garden was in front of the burning house where a lot of talking frogs where living. Aaand you just remembered the number 02210. These stories get easier to remember if you have more than 3 different types of digits ;) Funny thing.. you will probably still remember that number tomorrow while any other random number in your head would long be gone. I was able to remember 20 digit numbers like that without much practise.