Google is also often wrong. For example, my computer is set to US English, as is my profile. Yet somehow it still gets confused on decimals and commas (they are switched in my current country’s locale).

Also, if you use the Firefox search bar only the first 20 chars are sent to google, so longer calculations are truncated before they're calculated and wrong answers come back with no warning. Not a Google problem per se but a risk of using Google to calculate still.