You’d think that the word ‘billion’ would mean the same to all English speakers, but, in fact, the two different meanings of the word are vastly different – 1,000,000,000 and 1,000,000,000,000 (one thousand million and one million million). The first is the current ‘global’ understanding of the word (using the short scale, sometimes known as American usage), and the second, much larger number, uses the long scale or British usage. As the numbers get bigger, the difference between them gets larger, as the short scale increases by thousands (e.g. a trillion is a thousand billions, or 1012), and the long scale increases by millions (e.g. a trillion is a million (long scale) billions, or 1018).
Most countries use the short scale, these days, but many still use the long scale. Some countries, such as France and England, have used both scales at different times in history, so it’s important to check sources if you ever come across billion, trillion, etc in older publications.
The French word billion, German Billion; Dutch biljoen; Swedish biljon; Finnish biljoona; Danish billion; Spanish billón and the Portuguese word bilião all refer to 1012, being long scale terms. Therefore, each of these words translates to the modern English word: “trillion” (1012 in the short scale), and not “billion” (109 in the short scale).
On the other hand, the Brazilian Portuguese word bilhão (note the alternate spelling to the European Portuguese variant) and the Welsh word biliwn both refer to 109, being short scale terms. Each of these words translates to the English word “billion” (109 in the short scale). [Wikipedia.]
I think the best thing to do if you have to communicate in such large numbers is just to use the numerals instead of the words!