SB 3.11.41

daśottarādhikair yatra
 praviṣṭaḥ paramāṇuvat
lakṣyate ’ntar-gatāś cānye
 koṭiśo hy aṇḍa-rāśayaḥ
Word for word: 
daśa-uttara-adhikaiḥ — with ten times greater thickness; yatra — in which; praviṣṭaḥ — entered; parama-aṇu-vat — like atoms; lakṣyate — it (the mass of universes) appears; antaḥ-gatāḥ — come together; ca — and; anye — in the other; koṭiśaḥ — clustered; hi — for; aṇḍa-rāśayaḥ — huge combination of universes.
Translation: 
The layers or elements covering the universes are each ten times thicker than the one before, and all the universes clustered together appear like atoms in a huge combination.
Purport: 

The coverings of the universes are also constituted of the elements of earth, water, fire, air and ether, and each is ten times thicker than the one before. The first covering of the universe is earth, and it is ten times thicker than the universe itself. If the universe is four billion miles in size, then the size of the earthly covering of the universe is four billion times ten. The covering of water is ten times greater than the earthly covering, the covering of fire is ten times greater than the watery covering, the covering of air is ten times greater than that of the fire, the covering of ether is ten times greater still than that of air, and so on. The universe within the coverings of matter appears to be like an atom in comparison to the coverings, and the number of universes is unknown even to those who can estimate the coverings of the universes.