This question is not as easy as it looks. Historically, there are two naming systems for very large numbers, known as the “short scale” and the “long scale”. In the short scale, a billion is defined as a thousand million (i.e. 1,000,000,000 or 109), but in the long scale, a billion is defined as a million million (i.e. 1,000,000,000,000 or 1012). These two systems first arose in the 17th century in Europe. The long scale is the standard system in Germany and most other countries in continental Europe. So German uses the word “Billion” for a million million (i.e. 1,000,000,000,000 or 1012), and a thousand million (i.e. 1,000,000,000 or 109) is called “Milliarde”.
Until the 20th century, Britain and most other English-speaking countries also used the long scale, so the terms were usually similar to the German words. However, the early settlers in North America used the “short scale”, and this became the standard system in the USA. Due to the influence of American usage, especially in the development of computers, short scale numbers were often used even in British English, so the situation was extremely confusing. In 1974, the British government decided to adopt the system which was used in the USA, i.e. the ”short scale” system.
Problem solved? Yes and no. The official use is now the same in British and American English, and most other English-speaking countries now use the same system. But there are still people who prefer the traditional “long scale” system. This means that the short scale numbers should now be used when we translate into English. But when we translate from English, especially older texts, confusion may arise and it may be wise to find out which system is being used.
This history of the number systems has also created “false friends” for translators. A German “Billion” is not the same as an English “billion”. The words “Trillion” and “Quadrillion” are also misleading. And a German “Milliarde” is not a “milliard”.
Here is a short list of the German terms and their modern English equivalents (with the old British terms in red and italics):
103 Tausend thousand
106 Million million
109 Milliarde billion
thousand million / milliard
(Milliardär = billionaire)
1012 Billion trillion
billion
1015 Billiarde quadrillion
thousand billion /
billiard
1018 Trillion quintillion
trillion
1021 Trilliarde sextillion
thousand trillion
/ trilliard
1024 Quadrillion septillion
quadrillion
Another way of saying it
There is another way of naming big numbers which is not ambiguous, although it is not used in general counting and in texts about finance and investments. This system uses prefixes which are mainly derived from Greek, and it gives us a few familiar words such as kilometre, kilogram, megabyte and gigabyte. Each prefix has a rigidly defined value and does not change between German and English (except for minor spelling adjustments and the initial capital in most German contexts). The values are:
10 Deka-/deca- (zehn / ten)
102 Hekto-/hecto- (hundert / hundred)
103 kilo- (Tausend / thousand)
106 mega (Million / million)
109 giga- (Milliarde / billion)
1012 tera- (Billion / trillion)
1015 peta- (Billiarde / quadrillion)
1018 exa- (Trillion / quintillion)
1021 Zeta-/zetta- (Trilliarde / sextillion)
1024 yotta (Quadrillion / septillion)
There are also prefixes for numbers smaller than 1, for example Dezi-/deci-, Zenti-/centi-, milli-, Mikro-/micro-, nano-, Piko-/pico- etc. Familiar words including these prefixes include centimetre, milligram, millimetre and others.
There is more to be said about numbers in translation, for example the punctuation in numbers, the use of abbreviations in financial texts, the dimensions used in the building trade or industry and much more. But these are topics for another day. Watch this space.