you can also enter your equation into Google and it will solve or convert for you. You would enter "convert 0.5 km to miles" and it will spit out 0.5 kilometers = 0.310685596 miles.

Google will also do your child's algebra!! (If you can figure out how to enter in the equations correctly!). We had a heck of a time with it the other night to check DD's work, but eventually figured it out. Wish I could afford that $100 calculator for her (but then if I did that, I would have less $$ for me to buy cycling toys with!).