# A Zillion Troubles

If there is a word guaranteed to cause substantial confusion, it is billion. Until recently, most people in Britain took it to mean a million million (a 1 followed by 12 zeroes), whereas in the United States it has always meant a thousand million (a 1 followed by only 9 zeroes). There are very few situations in which a factor of a thousand difference is regarded as insignificant and the variation in definition has caused considerable confusion. The need for a common meaning for the word has caused us British largely to capitulate: in most fields now the American usage prevails and indeed it is now official Government policy to use the American billion in all its publications. But how did we get into this mess in the first place?

The system of naming large powers of ten seems to have first been worked out in France by a M. Chuquet in the 1480s. It was elegant and logical: starting with billion, multiples were derived based on powers of a million and named using a set of prefixes derived from the Latin numerals: bi–, tri–, quadr–, quint–, and so on, plus the suffix –illion derived from million. So a trillion was the third power of a million, a 1 followed by 18 zeroes. Over the following century, this system was adopted in much of continental Europe and in Britain.

Then something very strange and nearly disastrous happened. French speakers changed the system to one in which the multiples were not of a million, but only of a thousand. The OED remarks:

According to Littré, it was only in the middle of the 17th c. That the “erroneous” custom was established of dividing series of figures above a million into groups of three, and calling a thousand millions a billion, and a million millions a trillion, an entire perversion of the nomenclature of Chuquet and De la Roche.

The big problem was that the same words were used in both systems, leading inevitably to the confusion which continues to this day. The table below shows how the two systems relate. The numbers indicate the power of ten involved in each case, so that “9” means 10 to the power of 9 (109) or a 1 followed by 9 zeroes. All the prefixes are derived from Latin roots.

Number word Millions system Thousands system
million 6 6
billion 12 9
trillion 18 12
quintillion 30 18
sextillion 36 21
septillion 42 24
octillion 48 27
nonillion 54 30
decillion 60 33
undecillion 66 36
duodecillion 72 39
tredecillion 78 42
quattuordecillion 84 45
quindecillion 90 48
sexdecillion 96 51
septemdecillion 102 54
octodecillion 108 57
novemdecillion 114 60
vigintillion 120 63

As you can see, the separation between the thousands system and the millions system increases rapidly as you go upwards, so for example there is a huge difference of opinion between them about the number word centillion; in the thousands-factor system it amounts to 10303 but in the million-factor one it is 10600. As the number of elementary particles in the universe has been estimated at about 1085, there would seem to be little need for such large numbers, but this hasn’t stopped people inventing them. I have even found a reference to milli-millillion, which is 103000003; this makes the famous googol, which is a mere 10100, seem almost graspable (by the way, googol is possibly the only word in the English language which was invented by a nine-year-old, the nephew of Edward Kasner).

Some countries followed the “erroneous” new French practice while others stayed with the older one. In particular, the young United States took over the revised French system, but Britain didn’t. Just to confuse us all even further, the French made another flip of principle in 1948 and changed back to their original system, which was also re-adopted in French-speaking North America. Which system is used in each country and language depends in part on the point in history at which they came under the influence of one or other European country. Bernard Comrie of the Department of Linguistics at the University of Southern California in Los Angeles has surveyed a variety of languages with the help of subscribers to the Linguist List and has determined the following spheres of influence for the two systems:

Multiples of a million: German, Dutch, Swedish, Danish, Norwegian, Finnish, French (since 1948), Spanish (including American Spanish, though not Puerto Rico), Portuguese (European), Catalan, Galician, Hungarian, Polish, Czech, Slovak, Serbo-Croatian (Serbian, Croatian), Slovene, Hungarian. Multiples of a thousand: US English, Italian, Russian, Turkish, Greek, Portuguese (Brazilian).

Until comparatively recently, the confusion didn’t matter so much. It was only with raging inflation and the growth of international trade that problems began to be apparent. British taxpayers have in recent years become familiar with budgets and trade deficits measured in (small) billions; in the US, budget deficits have even reached the trillions, which is the largest number word that most English-speaking people have encountered. Larger ones usually appear in scientific or technical contexts in which scientific notation is more appropriate, or in which the standard set of prefixes agreed under the Système International (SI) system can be used. These also go up in multiples of a thousand but, being artificially constructed, do not conflict with either system:

Prefix Multiplier Notes
kilo– 3 From the Greek for “thousand” (introduced at the inception of the metric system in 1795 and retained in SI).
mega– 6 From the Greek for “large; great” (also predates SI units, with occasional examples back to 1868).
giga– 9 From the Greek for “giant”.
tera– 12 From the Greek for “monster”.
peta– 15 Seemingly an invented word based on the Greek prefix penta– (this being the fifth prefix in the series).
exa– 18 Apparently derived from the Greek prefix hexa– by deleting the first letter.
zetta– 21 Possibly derived from the Greek word for seven. However, it is also said to be adapted from the Italian sette, “seven”, which seems more likely.
yotta– 24 Similarly either derived from the Greek octa–, or from the Italian otto, “eight”, with the last letter changed to match that of the other prefixes.

Only the smaller prefixes are in anything like regular use even in technical contexts, though computing has started to speak of terabytes and to theorise about the need soon for petabyte levels of storage. They have had little or no impact on the language at large. Though mega– has taken on a fashionable role as an intensifier and a superlative of super– in words like megastar, it is primarily derived from the much older sense of “large”, as in words like megalith, “large stone”. There are the very tiniest signs that we may see giga– following it as linguistic inflation continues — a theme park at Kuala Lumpur in Malaysia is to be called GigaWorld because, according to its promoter, “Mega is too modest a term” for it.

There is another set of number words, which were introduced in countries using the original million-factor system to express the intermediate multiples of a thousand. The only one of these which has gained any currency in English is milliard (for a thousand million) but it must be quite unfamiliar to most people today. Further number names in this series can readily be derived by analogy: the next terms would be billiard (1015) and trilliard (1021) but I have never encountered either and they are not listed in the OED.

If your concern is only to express the hugeness of some number, without tying yourself down to anything so mundane or precise as actual numbers, you can use one or other of the hand-waving words we have in the language. Zillion I’ve used in the title, which is well-established and can be traced back at least as far as the 1940s and Damon Runyon; more recently, others have begun to appear, such as bazillion, kazillion, jillion, gazillion and squillion, hardly any of which have yet made the dictionaries, though the last two are fairly commonly encountered.

Page created 21 Jun. 1996
Last updated 28 Dec. 1996

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