How big is a billion ?

1,000,000,000,000

http://www.oxforddictionaries.com/words/how-many-is-a-billion

The American billion is 1,000,000,000; this was called, in Britain, until 1974, a thousand million or, more occasionnally, a milliard.

See Numberphile's video:

https://www.youtube.com/watch?v=C-52AI_ojyQ&index=39&list=PLt5AfwLFPxWLNZRKWlcRmTABh_SExiiCj

Yes in some countries a billion is  1 with 9 zeros and in others it is 1 with 12 zeros.

I think the 9 zeros is more common and it is the US one I believe.

MathsGod is British and I think that he is also correct. I think it England it is 1 with 12 zeros.

this is why scientific notation is so much better with very big and very tiny numbers :)

Thanks Melody, MrGenius and MathsGod1;

There are two systems: The short system, or short scale, and the long system, or long scale.

In the short system:

1,000,000,000 is a billion

1,000,000,000,000 is a trillion,

1,000,000,000,000,000 is a quadrillion, et caetera...

In the long system:

1,000,000,000 is a thousand million or, more occasionally, a milliard (I love this word )

1,000,000,000,000 is a billion

1,000,000,000,000,000 is a thousand billion or a billiard

and so on.

The short system has always been used in USA; it was officially adopted by UK in 1974.

But the long system is still used in almost every non-English-speaking countries in the World.