What difficulties do using non-standard units present for introducing measurement? What are the advantages of using non-standard units to introduce measurement? Please help ASAP!!!

Well, a statute mile such as we use on a car trip in the US is about 5,280 feet

However a Nautical mile, used for navigation is about 6076.118 feet
There is a reason those of us who play with sextants use nautical miles.
I guy named Napolean came up with the idea.
You see a degree of latitude (degrees above the equator ) is exactly 60 nautical miles so a "minute" of latitude is a nautical mile. By the way that only works for longitude at the equator because those lines come together as you move north or south from the equator.