Google calculator is one of the latest in the series of useful things to be found at www.google.com

**So... Increase my calculating power then?**

In its most basic form it's a calculator: type an algebraic expression into the google search box and instead of a page of search results you will get the result of the calculation. If instead you did want to see what the old wise ones had to say about "2+2" there's a link that will take you to a familiar search results page.

It's a fairly competent calculator. It knows about

operator precedence, i.e. 2+4*3 evaluates to 14 and not 18. The answer page displays the formula you inputted with the implied brackets in case you didn't know about operator precedence. You can evaluate more complex expressions using most of the functions you would find on your average calculator such as raising to a power (using either the ** or ^ notation), sine, arccos,

factorial,

exponential, cosh (but not arccosh). It does not seem to do any symbolic manipulation for example arctan(1) evaluates to 0.785398163 instead of π/4. It also does not include slightly less common functions such as the

gamma,

beta or polylogarithm functions.

On the plus side it handles binary, octal and hexadecimal. The default base is 10, the prefixes 0b,0o and 0x can be used, and the result can be converted into the base of your choice by appending "in base n" (with n being 2,8,10 or 16) to your query. You cannot do bitwise operations though.
It can also deal with complex numbers; if you search for e^(i*pi) you will get the expected answer and computations such as cos(i) yield the correct results.

If you ask it to perform a calculation it doesn't understand at all (for example arcsinh(2)) or in the case of errors such as an overflow (for example e^(e^8)) then you go straight to the search results page. In certain cases when it isn't quite sure if it should do a calculation or not I got both a search and a calculation result on the same page. I found this tended to happen if I didn't close brackets or when using words to input numbers.

**How many slugs in a pound?**

That's not all though! The Google calculator can convert measurements between different units, you can submit queries such as "4 km in furlongs" or "one horsepower in btu/hr". If you try and do something silly like "4 fathoms in bushels" in you will get a normal search results page. It is also capable of evaluating expressions like "1 kilo + 1 pound" or "1 watt * 1s". It is fully aware of the difference between imperial and american units for things such as gallons, but seems to always defaults to the american version, even on google.co.uk. If you want to use imperial units you will need to add the prefix "imperial" to your units (Thanks to wertperch for pointing this out). However it does not seem to be able to cope with the fact that many British people would like weights in pounds and stone, not just in stone or just in pounds.

Google takes all this one step further: you can do your sums in words (though why you would want to do this is beyond me). For example "twenty times the speed of light", "cube root of seven" or " two to the third" perform the appropriate calculation. You can also search for "How many x in a y" to perform unit conversions.

**The answer to life the universe and everything**
Google knows about many important constants, which may be referred to by their symbol such as G or c or by their name, for example "the speed of light", "The answer to life the universe and everything" or "permeability of free space". You can of course use these constants in your calculations (although it would be nice to be able to use more symbols such as μ_{0}). When using constants, Google will however sometimes decide that you weren't trying to perform a calculation, in particular it really doesn't like adding constants (for example c*(1+G) does not give a calculated result but c*(1+4) or c*(1*G) does) (thanks to syntax for noticing this).

Hmmm, not only is Google interested in the web sites you search for, it also wants the numbers you calculate with...

Sources:

http://www.google.com/help/features.html#calculator