Is it because of how you do mental math? I saw 6/10 and immediately mentally registered 3/5, which is a simpler number to mental math with, for me anyways.
Yeah I guess it is. I’m good at doing tenths. Fifths are weird and scary to me :)
So the km:mi ratio is somewhere between 60:100 and 66:100. I choose whichever one makes sense depending on the number in front of me.
6/10 = 5/10 + 1/10 or in words: divide by two and add a tenth!
Yes, this means both 90 and 100 km/h both covert to 60mph. Close enough!