In case you diddn't know, Google has a calculator built into its search, for example, type in 4+2 and it will say:

You can also do Minus (-), multiply (x or *), divide(/).
Although this seems like a simple calculator, it isn't. There are MANY MORE functions that it does.
you can use words or symbols, for example, "4 plus 2" does the same as 4 + 2.

You can also do more complicated equations, including "Square Root of 25", "pi squared", "3 over 9 (as in 9 divided by 3).

Calculator also supports conversions, such as:
20ft to cm
43 miles to km
10 USD to EUR (dollars to euros)

and it even has less common measures, including:
10 miles to furlongs
100F to Kelvin (temperatures)
1 marathon to miles
10 hands to cm (hands are used to measure horses generally)
1 firkin to litres
2 barrels to liters (as in beer barrels)
10 grains to mg (grains to milligrams)
1 light year to miles

and so on... (please comment if you find any more)


That isn't where it ends though.
There are some Easter Eggs in the system too!
The easter eggs that the internet have discovered so far are:

View: 720x127

View: 720x130

View: 717x142

if you find any more interesting things, please comment :P

PS: It can also do time. its not Google calculator, but it almost is!

Type in time and any:
City "Time in London"
Country "Time in Antarctica
Post/Zip Code "Time in SW1A 2AA"
The returned result is, the time and day, the time "code" (such as GMT(Greenwich mean time) or CEST(Central European Summer TIme), the Location:
eg: 18:38 Sunday (GMT) - London, SW1A 2AA, UK
(in case you wondered, SW1A 2AA is the post code for 10 downing street.