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  Mike Todd

Billion and beyond

There has always been confusion between what the British and the Americans call a billion. Historically, in the UK, a billion is 1,000,000,000,000 (10^12) but in the US it is only 1,000,000,000 (10^9).

The table below shows the differences between the two sets of numbers; the only one which is common to both systems is the million.

However, because of the confusion, the international scientific community started to adopt the US "short scale" version in the 1950s, and UK general usage followed suit (even though British colloquial use still occasionally reverts to the "long scale", and in British legal circles the long scale is applied).

The table shows the pattern of why there is a difference. In the UK system, an -illion is considered to be 1,000,000 so that each time you increase the value with 6 zeros, you go up the scale. So, a billion is really two -illions, or with 2*6 zeros, a trillion is with 3*6 zeros, a decillion is 10*6 zeros and so on, up to a centillion, which is 100-illions, or 600 zeros.

In the US, the name represents the number of groups of three zeros after the initial 1,000 - so that a billion is two groups of three after the 1,000, or 1,000,000,000 - a trillion is three groups of three, and a decillion is ten groups of three zeros after the 1,000 (a total of 33 zeros). The US centillion is therefore 1,000 followed by 300 zeros (or a total of 303).

The US system was modelled on the old French system, but in the 1940s, the French system was brought in line with the UK system.

US Name  Zeros  UK Name
million 6 million
billion 9 -
trillion 12 billion
quadrillion 15 -
quintillion 18 trillion
sextillion 21 -
septillion 24 quadrillion
octillion 27 -
nonillion 30 quintillion
decillion 33 -
undecillion 36 sextillion
duodecillion 39 -
tredecillion 42 septillion
quattuordecillion 45 -
quindecillion 48 octillion
sexdecillion 51 -
septendecillion 54 nonillion
octodecillion 57 -
novemdecillion 60 decillion
vigintillion 63 -
- 66 undecillion
- 72 duodecillion
- 78 tredecillion
- 84 quattuordecillion
- 90 quindecillion
- 96 sexdecillion
- 102 septendecillion
- 108 octodecillion
- 114 novemdecillion
- 120 vigintillion
centillion 303 -
- 600 centillion