No, 6400 is a number that no human can accurately visualize. It's not a metric thing, it's a numbers thing. https://gizmodo.com/how-to-comprehend-incomprehensibly-large-numbers-1531604757I think 95+% of the world can perfectly well envision what that is. Only 4.something % of the world population uses these archaic measurements, the rest of the planet moved on some 150 years ago.
Even Kim Peek, the inspiration for rain man, couldn't do that.