Pilots keep their logbook in decimal hours, and the tach meter (engine hours at a certain speed) and Hobbs meter (aircraft operated hours) are decimal too.

Each decimal hour (0.1) is equal to 6 minutes. So if I ‘fly’ for 1 hour and 13 minutes I log 1.2 hours. I don’t do the mental math though, I just record what the Hobbs says.