Thank you! I didn't include them because there aren't many, but I can expand a bit here.
Beyond 10, it's mostly classes of numbers that have unique forms, rather than the numbers themselves. So 15, 25, and 35 to some extent are somewhat of a stair pattern made of three squares, and they want to interlock nicely with each other. Things like powers of two also take on these sorts of interlocking forms, so maybe it's just numbers where I've memorized their doubled versions over time.
Low multiples of three from around 18 through 27 take on a sort of blobby trefoil shape and want to be divided into three parts. Higher, obvious multiples of three like 333 or 666 are similarly tri-lobed, but each lobe is a bit spikier in a way. I don't really have any strong associations with operations for these apart from splitting them into three. Again, I wonder if this is a sort of learned association from multiples of three that I encounter a lot.
Thank you. I would interview you exhaustively about this if I could :-), I find it so fascinating. Well, I'm still hoping for a part 2 sometime. I'd love to read whatever words and pictures you write about this. (To me, surprisingly, it seems not weird at all, although I have nothing like that.)
Beyond 10, it's mostly classes of numbers that have unique forms, rather than the numbers themselves. So 15, 25, and 35 to some extent are somewhat of a stair pattern made of three squares, and they want to interlock nicely with each other. Things like powers of two also take on these sorts of interlocking forms, so maybe it's just numbers where I've memorized their doubled versions over time.
Low multiples of three from around 18 through 27 take on a sort of blobby trefoil shape and want to be divided into three parts. Higher, obvious multiples of three like 333 or 666 are similarly tri-lobed, but each lobe is a bit spikier in a way. I don't really have any strong associations with operations for these apart from splitting them into three. Again, I wonder if this is a sort of learned association from multiples of three that I encounter a lot.