How many is a billion?
The answer may seem obvious, but the use of this word can lead to confusion.
In the UK and Ireland the word traditionally meant the number 1,000,000,000,000 (a million millions), which is called a trillion in the United States.
A billion in the United States is considerably smaller: only 1,000,000,000 (a thousand million).
The system used in America is called the short scale, whereas that formerly used in Britain and Ireland is called the long scale.
If you are a billionaire, you are clearly very rich whichever system you follow, but for scientists, such a discrepancy could make a big difference to the results of an experiment. Thankfully, therefore, there has been a move to unify usage in this area, and nowadays the American standard is almost always used in English on the opposite side of the Atlantic.
The British government officially adopted the use of the short scale in 1974 in an effort to avoid confusion. Interestingly, South Africa has clung to the old usage, with a billion meaning 1,000,000,000,000, and has introduced another word, milliard, to refer to the number 1,000,000,000.
This reflects usage in languages like French, which uses the words milliard and billion. In scientific subjects, however, a billion is a thousand million all over the English-speaking world. This has not put an end to confusion, though – other languages such as French, Spanish, and Dutch continue to use the long scale, where a billion means a million millions.
As well as milliard, some other large numbers have recently been added to the Cambridge English Dictionary. A googol is the number 10 to the 100th power (10 followed by 100 zeros), whereas a googolplex is the number 10 to the power of a googol. They join words like billion and trillion in the dictionary, as well as their humorous cousins, squillion and zillion.
These words are used to refer to very large, but not exact, numbers:
He made squillions from selling his business.
I’ve told you a zillion times not to do that.
While billionaires are increasingly common (especially measured by the short scale), the first googolaire (not really a word!) is yet to hit the headlines.