It's not so basic though. Google knows the current value of most currencies, for instance. It's actually more efficient for the central servers to pull that data and the clients to query once in a while, rather than every single client (local calculator) to constantly keep all that data up to date. And that's just the currencies.
Your query doesn't exactly work though, it's interpreted as "paris at speed of sound". However "time between amsterdam and paris at the speed of sound in milliseconds" does work, returning 1.26*10^6 ms.
Oh wow, even microparsec/kilofortnight in m/s works now. This did not work for many years, and prompted me to write my only ever e-mail to Google with a complaint about 5 years ago.
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.
