Trillion
A trillion is a number with two distinct definitions
Short scale
1,000,000,000,000, i.e. one million million, or 1012 (ten to the twelfth power), as defined on the short scale. This is now the meaning in both American and British English.
Long scale
1,000,000,000,000,000,000, i.e. 1018 (ten to the eighteenth power), as defined on the long scale. This is one million times larger than the short scale trillion. This is the former meaning in British English and the current use in many non-English-speaking countries.
Historic =====
Originally, the United Kingdom used the long scale trillion but since 1974, official UK statistics have used the short scale. Since the 1950s, the short scale has been increasingly used in technical writing and journalism, although the long scale definition still has some limited usage. American English has always used the short scale definition.
Worldwide