Old phone numbers in the U.S. had letters to denote the telephone exchange that handled any given number, a practice that lasted until the late 1970s.

An M with a small letter or set of letters above it stood for tens of thousands and higher. (Confusingly, in this instance the M represented the Greek ancestor of “myriad,” not the number 40.) ...

The two letter, five number format—or “2L-5N”—was eventually standardized throughout the country). Because these telephone exchanges could only facilitate around 10,000 subscribers, ...

The ancient Greeks were incredibly talented mathematicians—but they rarely used numbers in their math. Their particular specialty, geometry, dances around actual quantities, focusing on higher ...