Do you know that  a marathon is a long-distance running race with an official distance of 42.195 kilometres
I knew it in miles but not KM.  I'm not much of a runner, 5K is about my limit.  What about you?
Marathon
The marathon is a long-distance race with an official distance of 42.195 kilometres (approximately 26 miles 385 yards), usually run as a road race. The event was instituted in commemoration of the fabled run of the Greek soldier Pheidippides, a messenger from the Battle of Marathon to Athens, who reported the victory. The marathon can be completed by running or with a run/walk strategy. There are also wheelchair divisions.
The marathon was one of the original modern Olympic events in 1896, though the
running sections ranging from five kilometres (3.1 mi) to the marathon distance (42.195 kilometres, or 26 miles and 385 yards), depending on the race type. The related sport of duathlon is a combination of cycling and distance running. Previous versions of the modern pentathlon incorporated a three or four kilometre (1.9–2.5 mi) run, but changes to the official rules in 2008 meant the running sections are now divided into three separate legs of one kilometre each (0.6 mi).
Depending on the rules