Тим ·

Оказывается, что 24/7 в таком виде появилось только в 1983 году:

The Oxford English Dictionary (OED) defines the term as "twenty-four hours a day, seven days a week; constantly". It lists its first reference to 24/7 to be from a 1983 story in the US magazine Sports Illustrated in which Louisiana State University player Jerry Reynolds describes his jump shot in just such a way: 24-7-365. 24/7, Wikipedia