When is a billion not a billion?

If you had a choice of having a billion coins worth one cent each given to you in Finland or the United States, which would you take?

It's sort of a trick question.

It turns on how these countries name large numbers and that depends on whether they are a long-scale country or a short-scale country.

With the current financial crisis having everyone throwing around numbers in the billions and trillions, a look at naming large numbers might be in order.

Internationally, everything is fine up to a million. But after that things get tricky.

In the United States, a short-scale country, a billion (one followed by nine zeros) is a thousand million and a trillion (one followed by 12 zeros) is a thousand billion. So in short-scale countries, large numbers progress by being multiplied by a thousand. Most native English-speaking countries, such as Canada and Australia, are short-scale countries.

In long-scale countries, such as Finland, to get from one order of magnitude to another you multiply by a million. So a billion is a million million (one followed by 12 zeros) and a trillion is a million billion (one followed by 18 zeros.)

Long-scale countries are continental European countries and those whose language derives from them. There are more long-scale countries than short scale-countries.

For reasons of clarity, some long-scale countries use the word milliard for a short-scale billion and billiard for a short-scale trillion.

But there is yet another nomenclature for big numbers.

Greece uses short-scale, multiplying by 1,000, but a U.S. million is a hundred-myriad, a billion a bi-hundred-myriad and a trillion a tri-hundred myriad. China, Japan and the Koreas use variants of the myriad system.

That brings us to England, which started as a long-scale country. Remember, this is the country that adds superfluous letters to perfectly good words (programme, colour, tonne)

In the 1970s, the United Kingdom's government, media and other official agencies switched to the short-scale system. The British never used the word milliard, preferring instead thousand million.

So, let's confine ourselves henceforth to the short-scale system.

Multiplying a trillion by a thousand three more times we get a quadrillion, quintillion and sextillion. Zillion, by the way, is a generic term for a very large number but has no clearly defined numerical value.

So we come to a googol (note the spelling, not the same as the search engine). A googol is one followed by 100 zeros. It has no particular mathematical significance and its proper name is ten duotrigintillion on the short scale and 10 thousand sexdecillion on the long scale. A googolplex is one followed by a googol of zeroes.

Astronomer Carl Sagan once remarked that to write down a googolplex would take more space than is occupied by the known universe.

In 1960, along came the International System of Units (SI), a metric system that tried to give some clarity by using a prefix for each higher number. Each prefix represents a multiplication by a thousand as in the short-scale system.

Thus mega is a million, giga is a billion, tera is a trillion and so forth through peta, exa, zeta and yotta.

This is the system used to measure computer memory -- where we get gigabytes and terabytes.

Only three countries have not adopted the SI as their primary or sole system of measurement -- Liberia, Myanmar and the United States. Go figure.