Radius of visible universe is 10^60 plank length. Which gives a volume of 10^180 plank cubes. These are the units of building blocks of the Universe. And nothing can be smaller than the size of a plank cube.
You can divide the universal scale into 10 scales, each 10^6 orders apart from the other.
1. galaxies
2. stars
3. solar system
4. visible distance
5. cells
6. atoms
7. quarks
8. neutrinos
9. unknown
10. strings