These are decimal numbers, and dots above some of the digits make them recurring decimals. One dot means the digit under it repeats infinitely. In other words, it goes on forever (and ever and ever).

NPR's Scott Simon talks to math historian Glen Van Brummelen about his finding that the decimal point appeared in the 1440s, earlier than thought. How did the decimal point come to be? - the dot that ...

The humble decimal point may have been invented about 150 years before we previously thought. Experts had previously credited German mathematician Christopher Clavius for the innovation, but according ...