Giga-numbers: what's big in zeros

Q. An obvious place to start, but what exactly is a billion these days

A. That depends where you're from. In the UK a billion was traditionally 1 million million, but in recent years it has been harmonised with the American value - 1 thousand million, now the international standard - in order to minimise confusion. All UK government documents now use billion to mean 1,000,000,000 - what used to be known here as a milliard - and that's the figure you're hearing on the news when talking about national debts or population figures.

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Q. How did this state of affairs come about

A. According to some sources the system of naming powers of ten was worked out in France by a Monsieur Chuquet in the 1480s. Using million as the model multiples were derived based on powers of a million and named using a set of prefixes derived from Latin: thus bi- (billion), tri- (trillion), quadr- (quadrillion), etc. This system was pretty quickly adopted throughout much of Europe and exported around the world during European colonial expansion

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However, in the mid 17th century the French adopted a system based on multiples of a thousand. This was also adopted by the USA after independence, presumably to cock a snook at the British. The problem was, while the values changed, the names didn't.

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Just to complicate matters even further, those crazy French and their colonies changed back to the million system in 1948.

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Q. So who uses which

A. Which system is used by which countries is largely a result of who came under who's sphere of influence. So, while the international standard may be 1,000,000,000 - and the USA, Italy, Russia, Turkey, Greece and Brazil all recognise this value - many countries still adhere to the old system, notably the Scandinavian countries, France, Spain and Spanish South America (though not Puerto Rico, which is pretty much part of the USA), Portugal, Hungary, Germany, Czechoslovakia and Poland.

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Q. Confusing. What about trillion and the rest

A. Depends on what system you're using, the thousand or the million. For example, a trillion is either 1,000,000,000,000,000 or 1,000,000,000,000,000,000, the second of which is a considerably bigger number than the first. So you have quadrillions (24 or 15 0s), quintillions (30 or 18 0s), sextillion (36 or 21 0s), septillion (42 or 24 0s), octillion (48 or 27 0s) and so on. By this stage the difference in value is astronomic, but, luckily, it is unlikely to ever affect you or I, as such figures are only ever used by scientists and they tend to express vast numbers as 'to the power of'.

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Q. And what's a googol

A. Ten to the power of 100. That is 1 followed by 100 0s.

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Q. What about giga and mega

A. Well, you have kilo- (3 0s), mega- (6 0s), giga- (9 0s), tera- (12 os), peta- (15 os), exa- (18 os), zetta- (21 0s) and yotta- (24 0s). So, when your new PC is released with 2 yottabytes of memory, you'll know you've got a good deal.

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Q. Any other anomalies

A. In India the use of a couple of time-honoured numerical values have survived the pressures of colonialism and internationalism, lakhs and crores. A lakh is 100,000 and 100 lakhs is a crore, or 10,000,000.

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Q. And zillion

A. Not a real number - though it dates back to at least the 1940s. Along with squillion and the like it is just used to infer an unfeasibly large, though non-specific, number.

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For more on Phrases & Sayings click here

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By Simon Smith