If I put .6 kilometers ^2 in acres into Google I get 148.263229 acres. But if I convert .6 kilometers to miles first .0.372822715 miles and then do 0.372822715 miles ^2 in acres I get 238.606538 acres?
UPDATE: The correct answer is, of course, 90 acres.
Not So Fast 
0.6 km^2 != 0.3728 mi^2
This is because .6 km^2 is an area whereas .6 km is a linear distance. You need to square the conversion factor from km -> mi.
So instead of multiplying your .6 by 0.62, multiply it by 0.3844 before you convert the square miles to acres.
*eyes glazed over*
It took me a while, and a slide rule, but I get it now.
I think I filled my math quota for the next 5 years.
Here’s a better way to think about it…
Pretend that 1km = .5 miles…
Now pretend you have a square that is 4km on all sides… this thing would be 16km^2, right?
If you convert 16km to miles you get 8mi… but picture the square in your head… it’s actually only 2mi on all sides… or 4mi^2.
And if you sketch that picture out on graph paper it sort of makes a little more sense… either that or I’m just one of those crazy math nerds.
…which is probably true. Maybe you should just disregard this entire post.
NERD! Yes, you are one of those crazy math nerds. But that is, more or less, how I finally figured out where I went wrong. It’s stuff like that that has plagued me since 4th grade.
Boy, do I feel stupid.