All of these things work in Google, btw. Google has one of the best unit conversion tools, and it's built into the search.
https://i.redditmedia.com/4FDIQLPJFtaOSXIDOlj6I9lCpVYdz8O06Y...
Currencies I can understand hitting a remote server, but general unit conversion and basic arithmetic?
10EUR + 11 USD + 1500 USD + 500CAD in ZAR
Unfortunaetly, the conversion 30 miles per gallon in liter/100 km still displays an equal sign, which is technically wrong. However, this conversion is so useful, that I won't complain about it.