I would basically just use the one-digit to disambiguate the rest of the number sequence. I wouldn’t combine the pebble with the numbers like you’re suggesting.
For 123.456 I would do: (12)(3)(pebble)(45).
For 12.345 I would do: (12)(pebble)(34)(5)
In the past, I remember experimenting with memorizing simple equations and whenever I tried to combine an operator with a number (I had a phonetic system of sorts for equations at the time) my recall would deteriorate. Because of this, I like to keep certain images separate and consistent for my own sake.
Also if by nested lists, you mean an index peg such as a category system, you should check out my study on pegs in the topic [Systems analysis of visual memory systems].(Systems analysis of visual memory systems). The one category system didn’t fare any better than a few other systems even though it seems more elegant. But it looks like it is a personal preference and that practice time makes the difference.
Thanks, I’ll read into it. I’ve seen your thread pop up, but I haven’t really sat down and analyzed it.