I received a 24-digit number at the office (801305102250926760572339), and I needed it at home the next day. I could have written it on a piece of paper and stuck it in my wallet, or … used the memory system. It took me a couple of minutes to come up with the following phantasmagoria:
I’m in my office (80) and a cosmic-ray atom (13) strikes me, interrupting me while I’m whistling (05 – ignore the ‘ng’ at the end since I’m doing numbers two-at-a-time) and rolling dice (10). The dice glow like neon (22) and have little wheels (50) on them. They roll off the end of the desk into a pan (92) and I shake (67) them over a fire until they are ashes (60). All that’s left is a logo (57) with a name (23) and some ambience (39).
I remembered it without difficulty the next day and will now proceed to forget it, or file it away in long-term memory, depending on whether I think I’ll need to use it again soon.
This was a pretty good one – I really paid attention to all the senses: hearing the whistling, the dice rolling and sizzling in the pan; smelling the burning plastic as they turned into ashes; feeling the atom strike me. I also spent extra time finding good phantasmagoria words: starting with the permanent pegs that are part of me, and branching out to sound-alike words that fitted the phantasmagoria better.
The memory pros can do this much faster and with much longer numbers. I think Eran Katz routinely demos with 100 read off at conversational speed. I presume they practice it all the time. I use phantasmagorias a couple of times a month, not for showing off, but for saving myself trouble. Definitely worth a couple of minutes.