Today's Mind-Blowing Fact:
Using https://en.wikipedia.org/wiki/Hard_disk_drive#History as my guide and a desktop calculator as my lantern (did I get that right?), I can express the bit density of a hard drive in black-and-white printing terms to really muddle the concepts.
The first HDD ever had a "DPI" of nearly 45.
The current state of the art in-production HDD has a "DPI" of 1.2 million.