In what situation would you be adding 7/16ths of an inch to 7/8 of a mile? If you have such crazy tolerances you shouldn't be using fractions from the start. And even if you did, with imperial system you could just write '7/8 mile and 7/16th of an inch' or '7/8 mi. 7/16 " ' and when they measure it out they will measure 7/8 of a mile, then add on that 7/16 inch.

And whatever you are measuring that length with, fucking awesome job getting 1/16 or better tolerances over that amount of distance with .