I woke up at night with an idea to imagine as much as possible in my mind. not relying on numbers.
 10, 100, 1000 ... I realized that I can not keep more than 5 -10 numbers in my head.
I started to build a million with the help of small groups. : two rows of 5 -10. 5 times 10 - 50. 2 times 50 - 100. All this was in the same space. and I could keep a thousand in my head clearly.
Of course at every point in time I did not track every unit. but with this approach I felt a real scale. further went to be more difficult, because you had to keep in mind not only 10 groups, but also several levels of scaling, but getting used to, I reached a million
 million, it's not so much, as it seemed to me)

I represented a little differently than here drawn. To separate the groups, I used space, not color.