It might be fake news, but I remember a story of a Seattle radio station reporting on an unusual cold snap. The station periodically broke into its programming to report on the temperature, which was rapidly dropping to unusual levels. “Folks, the temperature out at the airport is now 7 degrees.” A little while later…

It is a difficult concept. Sure, business people had the concept of zero (as well as negative numbers), but there is a philosophical leap between having zero mean “nothing”, as I have no fish, and having zero represent a number, as in “the temperature today is 0 degrees”.