Let’s not forget the teachings of Dale Carnegie…
In the memory lessons of the class, we’re taught that through relating mental imagery and the memorization of a few key concepts, we can actually store 42+ units of information (he claims infinite, but I’ve never seen more than 42)
The process is his “one-run, two-zoo” paired listing…
For each paired list, the person visualizes a scenario in their head involving the number/item they need to remember.
I can personally remember up to 21 groups of numbers (3-4 in size) for rapid recall… But I haven’t been practicing nearly long enough.