to be exact, a scale mile is 20'7.5". here is how:
1/4 mile = 1320 ft
1320 ft/64 = 20.625 ft.
But that is in decimals so you have to convert from decimals back to the unit system.
so .625=x/12........and x=7.5 inches
i don't want to be picky or anything but this could affect your times by .1 sec which people in real life are really anal about sometimes
