Size of Atoms

Did the philosopher make statements about the likely size of atoms?

A rock might be the size of one's hand. It might subdivide into, say, one million pebbles. Let's say each of those subdivides into one million grains of sand. Let's say each of those subdivides into one million particles of powder. Each of those subdivides into one million atoms.

1,000,000(pebbles)X1,000,000=1,000,000,000,000(1 trillion grains of sand) ...X1,000,000=1,000,000,000,000,000,000(1 million trillion particle of powder)
...X1,000,000=1,000,000,000,000,000,000,000,000(1 trillion trillion atoms)

This sounds like it could be right (in a general way).