Last update:
3-May-2004
©1996-2009
Mike Todd
Billion and beyond
There has long been confusion between what the British and the Americans call a billion (and beyond). 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, and anyone writing on the international stage needs to be aware of the ambiguities (especially as the discrepancies increase significantly with larger nubers).
However, because of the confusion, the international scientific community did start to adopt the US-adopted "short scale" version in the 1950s, and since the 1970s, UK general usage followed suit (even though British colloquial use still occasionally reverts to the "long scale").
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 actually modelled on the old French system but, ironically, in the 1940s, the French system was brought in line with the old 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 |